Reference Tables & Cheat Sheets

Free reference tables and cheat sheets for developers, students and everyday use — HTTP status codes, the ASCII table, HTML entities, color codes, unit conversion charts, math tables and more. Every chart is accurate, printable, and cross-linked to the matching converter tool.

World & Countries

• List of Countries of the World — Flags & Codes — Complete list of all countries of the world with flags, ISO country codes and continents. Browse by continent or region (Middle East, EU).
• Countries in Africa — List of all countries in Africa with flags and ISO codes — from Algeria and Nigeria to South Africa and Kenya.
• Countries in Asia — List of all countries in Asia with flags and ISO codes — including China, India, Japan, Indonesia and the Middle East.
• Countries in Europe — List of all countries in Europe with flags and ISO codes — including the UK, Germany, France, Italy and Russia.
• Countries in North America — List of countries in North America with flags and ISO codes — USA, Canada, Mexico, Central America and the Caribbean.
• Countries in South America — List of all countries in South America with flags and ISO codes — Brazil, Argentina, Colombia, Peru and more.
• Countries in Oceania — List of countries in Oceania with flags and ISO codes — Australia, New Zealand, Fiji and the Pacific islands.
• Largest Countries in the World by Area — The largest countries in the world by area: Russia, Canada, China, USA, Brazil, Australia and more, ranked with their size in km².
• 7 Continents and 5 Oceans — Names & Sizes — The 7 continents and 5 oceans of the world with their areas and populations. Asia, Africa, Europe, Americas, Oceania, Antarctica and the oceans.
• IATA Airport Codes — Major World Airports — IATA airport codes list: 3-letter codes for major airports — ATL, LHR, DXB, JFK, LAX, CDG, HND and more, with airport name and city.
• Country Calling Codes — International Dialing Codes — Country calling codes list with flags: international phone dialing codes for the US (+1), UK (+44), India (+91) and many more countries.
• Phone Number Formats by Country — Phone number formats by country with calling codes and examples: US +1, UK +44, India +91, Germany +49 and more.
• Postal Code Formats by Country (ZIP Codes) — Postal / ZIP code formats by country with examples: US (NNNNN), UK (AANA NAA), Canada (ANA NAN), India, Japan and more.
• Date Formats by Country (MM/DD/YYYY vs DD/MM/YYYY) — Date formats around the world: US MM/DD/YYYY, Europe DD/MM/YYYY, ISO 8601 YYYY-MM-DD. How different countries write dates.
• Which Side of the Road — Drive Left or Right by Country — Which countries drive on the left or right side of the road. List of left-driving countries (UK, Japan, India, Australia) and the rest.

Regions & Blocs

• Middle East Countries List — Flags & Codes — List of Middle East countries with flags and ISO codes: Saudi Arabia, UAE, Iran, Iraq, Israel, Turkey, Egypt and more.
• GCC Countries List (Gulf Cooperation Council) — The 6 GCC (Gulf Cooperation Council) countries with flags and ISO codes: Saudi Arabia, UAE, Qatar, Kuwait, Bahrain and Oman.
• ASEAN Countries List (Southeast Asia) — List of the 10 ASEAN member countries (Association of Southeast Asian Nations) with flags and ISO codes: Indonesia, Thailand, Vietnam, Philippines and more.
• South Asia Countries List (SAARC) — List of South Asia / SAARC countries with flags and ISO codes: India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan, Maldives and Afghanistan.
• Central Asia Countries List — List of Central Asia countries with flags and ISO codes: Kazakhstan, Uzbekistan, Turkmenistan, Kyrgyzstan and Tajikistan.
• East Asia Countries List — List of East Asia countries with flags and ISO codes: China, Japan, South Korea, North Korea, Mongolia and Taiwan.
• European Union Countries List (27 Members) — List of all 27 European Union (EU) member countries with flags and ISO codes — Germany, France, Italy, Spain, Poland and more.
• Nordic Countries List (Scandinavia) — The Nordic countries / Scandinavia with flags and ISO codes: Denmark, Sweden, Norway, Finland and Iceland.
• Balkan Countries List — List of Balkan countries (Southeast Europe) with flags and ISO codes: Greece, Romania, Serbia, Croatia, Bulgaria and more.
• North Africa Countries List — List of North Africa countries with flags and ISO codes: Egypt, Algeria, Morocco, Tunisia, Libya and Sudan.
• West Africa Countries List (ECOWAS) — List of West Africa countries with flags and ISO codes: Nigeria, Ghana, Senegal, Ivory Coast, Mali and more.
• East Africa Countries List — List of East Africa countries with flags and ISO codes: Kenya, Ethiopia, Tanzania, Uganda, Rwanda and more.
• Central Africa Countries List — List of Central (Middle) Africa countries with flags and ISO codes: DR Congo, Cameroon, Chad, Angola, Gabon and more.
• Southern Africa Countries List — List of Southern Africa countries with flags and ISO codes: South Africa, Namibia, Botswana, Lesotho and Eswatini.
• Caribbean Countries List — List of Caribbean island nations with flags and ISO codes: Cuba, Jamaica, Haiti, Dominican Republic, Bahamas and more.
• Central America Countries List — The 7 Central America countries with flags and ISO codes: Guatemala, Costa Rica, Panama, Honduras, El Salvador, Nicaragua and Belize.
• Latin America Countries List — List of Latin America countries with flags and ISO codes: Brazil, Mexico, Argentina, Colombia, Peru and the rest of Spanish- and Portuguese-speaking America.
• G7 Countries List — The G7 (Group of Seven) member countries with flags and ISO codes: USA, Canada, UK, France, Germany, Italy and Japan.
• G20 Countries List — The G20 member countries with flags and ISO codes: the US, China, India, Brazil, Japan, Germany and more major economies.
• BRICS Countries List — The BRICS countries with flags and ISO codes: Brazil, Russia, India, China and South Africa, plus 2024 members.

Cheat Sheets

• Git Cheat Sheet — Common Commands — Git cheat sheet of the most-used commands: init, clone, add, commit, branch, merge, push, pull, log, reset, revert and stash. Quick Git reference.
• Linux Commands Cheat Sheet — Linux/bash commands cheat sheet: ls, cd, cp, mv, rm, chmod, grep, find, ps, kill, tar, ssh and more. Essential terminal command reference.
• Docker Commands Cheat Sheet — Docker cheat sheet: run, ps, build, pull, exec, logs, compose up/down and prune. Essential Docker container and image commands.
• npm Commands Cheat Sheet — npm cheat sheet: init, install, uninstall, update, run, start, test, ls and npx. Common Node.js package manager commands.
• Bash Scripting Cheat Sheet — Bash shell scripting cheat sheet: variables, if conditions, test operators, for/while loops, functions and special variables ($?, $#, $@).
• SQL Cheat Sheet — Commands & Syntax — SQL cheat sheet: SELECT, WHERE, JOIN, GROUP BY, INSERT, UPDATE, DELETE and data types. Quick reference for MySQL, PostgreSQL and SQLite.
• Python Cheat Sheet — Syntax Basics — Python cheat sheet: variables, lists, dictionaries, loops, functions, comprehensions and string basics. Quick Python syntax reference.
• JavaScript Array Methods Cheat Sheet — JavaScript array methods cheat sheet: map, filter, reduce, forEach, find, push, pop, slice, splice, sort and more with descriptions.
• Vim Cheat Sheet — Commands Reference — Vim / Vi cheat sheet: modes, cursor movement, editing, search and save/quit commands. Essential Vim keyboard reference.
• CSS Flexbox Cheat Sheet — CSS Flexbox cheat sheet: flex-direction, justify-content, align-items, flex-wrap, gap and item properties like flex-grow and order.
• CSS Grid Cheat Sheet — CSS Grid cheat sheet: grid-template-columns/rows, repeat(), minmax(), gap, grid-column, grid-row and grid-area for 2D layouts.
• Markdown Cheat Sheet — Syntax Reference — Markdown cheat sheet with syntax for headings, bold, italic, links, images, lists, code blocks and tables. For GitHub, Reddit and docs.
• YAML Cheat Sheet — Syntax Reference — YAML syntax cheat sheet: key-value pairs, lists, nesting, inline maps, multiline strings and comments. For Docker, Kubernetes and CI configs.
• Regex Cheat Sheet — Regular Expression Reference — Regular expression cheat sheet: character classes, anchors, quantifiers, groups and lookarounds with examples. Works in JavaScript, Python, PHP and more.
• SQL Joins Explained (INNER, LEFT, RIGHT, FULL) — SQL joins reference: INNER, LEFT, RIGHT, FULL OUTER, CROSS and SELF joins explained with what each returns and an example.
• PowerShell Cheat Sheet — Common Cmdlets — PowerShell cheat sheet: Get-ChildItem, Set-Location, Get-Content, Get-Process, Where-Object and more cmdlets with their aliases.
• Windows Keyboard Shortcuts List — Windows keyboard shortcuts: Ctrl+C/V, Alt+Tab, Win+D, Win+E, Win+Shift+S, Ctrl+Shift+Esc and more essential shortcuts.
• Mac Keyboard Shortcuts List (macOS) — Mac keyboard shortcuts: Command+C/V, Cmd+Space (Spotlight), Cmd+Tab, Cmd+Shift+3/4 screenshots and more macOS shortcuts.
• Cron Cheat Sheet — Crontab Syntax & Examples — Cron / crontab cheat sheet: the five fields explained plus common schedule examples (every minute, hourly, daily, weekdays, @reboot).
• CSS Units Reference — px, em, rem, vw, vh — CSS units cheat sheet explaining px, pt, em, rem, %, vw, vh, vmin, vmax, ch and fr — when to use absolute vs relative units in responsive design.

Web & Development

• HTTP Status Codes — Complete List — Complete list of HTTP status codes (1xx–5xx) and their meanings: 200 OK, 301, 302, 401, 403, 404, 429, 500, 502, 503 and more. Quick reference for developers.
• HTTP Methods (Verbs) — GET, POST, PUT, DELETE — HTTP request methods reference: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS — with safe and idempotent properties for REST APIs.
• HTTP Headers List — Request & Response Reference — Common HTTP headers reference: Content-Type, Authorization, Cache-Control, Cookie, CORS and security headers explained for requests and responses.
• Common Port Numbers List (TCP/UDP) — Common network port numbers reference: HTTP 80, HTTPS 443, SSH 22, FTP 21, SMTP 25, MySQL 3306 and more well-known TCP/UDP ports.
• CIDR Subnet Mask Table (/8 to /32) — CIDR to subnet mask cheat sheet: every prefix /0 to /32 with its subnet mask and usable host count. IP subnetting reference.
• Private IP Ranges & IP Address Classes — Private IP address ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), loopback and link-local, plus IPv4 address classes A to E.
• DNS Record Types Explained (A, CNAME, MX, TXT) — DNS record types reference: A, AAAA, CNAME, MX, TXT, NS, SOA, PTR, SRV and CAA records explained. What each DNS record does.
• OSI Model — 7 Layers Explained — The OSI model 7 layers explained: Physical, Data Link, Network, Transport, Session, Presentation and Application — with examples and a mnemonic.
• HTML Tags List — Elements Reference — HTML tags list reference: structure, text, list, media, form and table elements with what each does. Common HTML elements cheat sheet.
• HTML Input Types Reference — HTML input types list for the input element: text, email, number, date, color, range, checkbox, radio, file and more, with descriptions.
• HTML Entity Codes — Reference Table — Complete HTML entity codes reference: named and numeric codes for & < > copyright, trademark, currency, arrows, math and special symbols. Copy-ready HTML character codes.
• MIME Types List — File Extensions & Content-Type — Common MIME types and file extensions reference: JSON, HTML, CSS, PNG, JPEG, PDF, MP4, fonts and Office documents. Content-Type values for the web.
• JavaScript Key Codes — keyCode & event.key Table — JavaScript keyboard key codes reference: event.keyCode and event.key values for Enter, Tab, Esc, arrows, letters and function keys.
• ANSI Color Codes — Terminal Text Colors — ANSI escape color codes for terminal text: foreground (30-37), bright (90-97), background (40-47) and styles like bold and underline.
• Escape Sequences Reference (\n, \t, \r) — Backslash escape sequences reference: newline, tab, carriage return, quotes, unicode and hex. Used in C, JavaScript, Python, Java and PHP strings.
• Linux Signals List (SIGKILL 9, SIGTERM 15) — Linux signals reference: SIGKILL (9), SIGTERM (15), SIGHUP (1), SIGINT (2) and more, with their numbers and meanings for the kill command.
• Internet TLDs List — Domain Extensions (.com, .org) — Internet TLD list: generic domains (.com, .org, .net, .io) and country-code TLDs (.uk, .de, .jp). Domain name extensions explained.
• Common File Extensions List by Type — Common file extensions list grouped by type: images (jpg, png), documents (pdf, docx), audio/video, code and archives.
• HTTP Cache Headers Explained (Cache-Control, ETag) — HTTP caching headers reference: Cache-Control (max-age, no-cache, no-store, public, private, immutable), ETag, Last-Modified, Expires and Vary.
• WCAG Contrast Ratio Levels (AA & AAA) — WCAG colour contrast requirements: AA 4.5:1 and AAA 7:1 for normal text, 3:1 for large text and UI components. Accessibility reference.
• chmod Permissions Chart (644, 755, 777) — chmod permissions chart: octal digits 0-7 explained (read 4, write 2, execute 1) plus common modes like 644, 755, 700 and 777 with symbolic notation.

Numbers & Encoding

• ASCII Table — Complete ASCII table (0 to 127) with decimal, hexadecimal, octal and binary codes for every character, including control characters. Free quick-reference chart.
• Binary Alphabet — Letters & Numbers in Binary — Binary alphabet chart: every letter A–Z, a–z and digit 0–9 in 8-bit binary code (based on ASCII). Read and write text in binary.
• Binary Numbers 1 to 100 Chart — Binary numbers from 1 to 100: every decimal value with its binary (base-2) equivalent. Decimal to binary reference chart.
• Binary / Hex / Decimal Table (0–255) — Binary, hexadecimal, octal and decimal conversion table for 0 to 255. One-byte number base reference with 8-bit binary and hex codes.
• Powers of 2 Table (2^0 to 2^64) — Powers of 2 table from 2^0 to 2^64 with exact values. Reference for binary, bytes, memory sizes and computing.
• Powers of 10 Table — Powers of 10 table from 10^-12 to 10^12 with values and names (thousand, million, billion, trillion). Scientific notation reference.
• Truth Tables — AND, OR, XOR, NOT Logic — Boolean logic truth tables for AND, OR, XOR, NAND, NOR, XNOR and NOT. Digital logic reference with all input combinations.
• Morse Code Chart — Alphabet, Numbers & Punctuation — Complete Morse code chart: the full alphabet (A–Z), numbers 0–9 and punctuation in dots and dashes. Learn and translate Morse code.
• NATO Phonetic Alphabet (Alpha Bravo Charlie) — The NATO phonetic alphabet chart: Alpha, Bravo, Charlie to Zulu, plus numbers. Used for clear spelling over radio and phone.
• Braille Alphabet Chart (A–Z) — Braille alphabet chart showing the dot pattern for every letter A to Z. Learn and reference the Braille reading system.
• Alt Codes — Symbols Keyboard Shortcuts — Alt codes chart: type symbols, currency and accented characters with Alt + number. Copyright ©, trademark ™, degree °, euro € and more.
• Data Storage Units Chart — Bit, Byte, KB, MB, GB, TB — Digital storage units explained: bit, byte, kilobyte, megabyte, gigabyte, terabyte and up — with decimal vs binary (KB vs KiB) sizes.
• Metric Prefixes Chart (SI) — Kilo, Mega, Giga, Milli — Metric SI prefixes table from yotta (10^24) to yocto (10^-24) with symbols and factors: kilo, mega, giga, tera, milli, micro, nano and more.
• Large Number Names — Million, Billion, Trillion, Googol — Names of large numbers (short scale): thousand, million, billion, trillion, quadrillion up to googol — with powers of 10 and zero counts.

Color

• HTML Color Codes & CSS Color Names Chart — HTML color codes chart with CSS color names, hex codes and RGB values — red, blue, green, gold, teal and more. Copy hex/RGB color codes for web design.
• Web-Safe Colors — 216 Color Palette with Hex Codes — The 216 web-safe colors palette with hex codes. Evenly spaced RGB values (00, 33, 66, 99, CC, FF) for cross-browser color reference.
• RGB vs CMYK — Color Models Compared — RGB vs CMYK explained: additive screen colour (red, green, blue) versus subtractive print colour (cyan, magenta, yellow, black). When to use each.
• Color Blindness Types Explained — Types of color blindness: deuteranomaly, protanopia, deuteranopia, tritanopia and achromatopsia — red-green and blue-yellow deficiencies explained.

Units & Measurement

• CM to Inches Chart — Centimeters to Inches — Centimeters to inches (cm to inches) conversion chart with formula. Quick reference for lengths and heights. 1 inch = 2.54 cm.
• Inches to CM Chart — Inches to Centimeters — Inches to centimeters (inches to cm) conversion chart and formula. 1 inch = 2.54 cm. Quick reference for lengths.
• MM to Inches Chart — Millimeters to Inches — Millimeters to inches (mm to inches) conversion chart with formula. 1 inch = 25.4 mm. Reference for tools and engineering.
• Feet to Inches Chart — Feet to inches conversion chart and formula. 1 foot = 12 inches. Length conversion reference.
• Feet to Meters Chart — Feet to meters (ft to m) conversion chart with formula. 1 foot = 0.3048 m. Reference for height and distance.
• Meters to Feet Chart — Meters to feet (m to ft) conversion chart with formula. 1 meter = 3.28084 feet. Length and height reference.
• KM to Miles Chart — Kilometers to Miles — Kilometers to miles (km to miles) conversion chart with formula. 1 km = 0.621371 miles. Distance conversion reference.
• Miles to KM Chart — Miles to Kilometers — Miles to kilometers (miles to km) conversion chart with formula. 1 mile = 1.609344 km. Distance conversion reference.
• MPH to KM/H Chart — Miles per hour to kilometers per hour (mph to km/h) conversion chart with formula. 1 mph = 1.609 km/h.
• KM/H to MPH Chart — Kilometers per hour to miles per hour (km/h to mph) conversion chart with formula. 1 km/h = 0.621 mph.
• KG to LBS Chart — Kilograms to Pounds Conversion — Kilograms to pounds (kg to lbs) conversion chart for common weights, with the conversion formula. 1 kg = 2.20462 lb.
• LBS to KG Chart — Pounds to Kilograms — Pounds to kilograms (lbs to kg) conversion chart with formula. 1 lb = 0.453592 kg.
• Ounces to Grams Chart — Ounces to grams (oz to g) conversion chart with formula. 1 ounce = 28.3495 grams. Weight conversion reference.
• Grams to Ounces Chart — Grams to ounces (g to oz) conversion chart with formula. 1 gram = 0.035274 oz. Weight conversion reference.
• Celsius to Fahrenheit Chart (°C to °F) — Celsius to Fahrenheit (°C to °F) conversion chart with formula. Includes body temperature, freezing and boiling points.
• Fahrenheit to Celsius Chart (°F to °C) — Fahrenheit to Celsius (°F to °C) conversion chart with formula. Body temperature, freezing, boiling and oven temperatures.
• Liters to Gallons Chart — Liters to US gallons conversion chart with formula. 1 US gallon = 3.785 liters. Volume conversion reference.
• Gallons to Liters Chart — US gallons to liters conversion chart with formula. 1 US gallon = 3.78541 liters. Volume conversion reference.
• Paper Sizes Chart — A4, A3, Letter (mm & inches) — Paper sizes chart: ISO A series (A0, A1, A2, A3, A4, A5) and US Letter, Legal, Tabloid — dimensions in millimetres and inches.
• AWG Wire Gauge Chart (Diameter in mm) — AWG wire gauge chart: American Wire Gauge sizes to diameter in millimetres. Lower gauge = thicker wire. From 4/0 to 24 AWG.

Body & Sizes

• BMI Chart — Body Mass Index Categories — BMI chart with Body Mass Index categories: underweight, normal, overweight and obese ranges. BMI = weight (kg) ÷ height (m²).
• Shoe Size Chart — US, UK & EU Conversion — Shoe size conversion chart for US, UK and EU sizes (men and women). Quick reference to convert between international shoe sizes.
• Ring Size Chart — US Sizes & mm — Ring size chart matching US ring sizes to inside diameter and circumference in millimetres. Find your ring size by measurement.
• Clothing Size Chart — US, UK & EU — Clothing size chart converting XS to XXL between US, UK and EU sizes for women and men, with chest measurements.

Cooking & Home

• Cooking Conversions Chart — Cups, Tbsp, Tsp, ml — Cooking measurement conversions: teaspoons, tablespoons, cups, fluid ounces, pints, quarts and gallons to millilitres. Recipe conversion chart.
• Oven Temperature Conversion (°C, °F, Gas Mark) — Oven temperature conversion chart: Celsius, Fahrenheit and gas mark equivalents for baking and roasting.
• Meat Cooking Temperatures Chart (Safe Internal Temps) — Safe meat cooking temperatures chart (USDA): beef 145°F, ground meat 160°F, poultry 165°F, pork 145°F, fish 145°F — in °F and °C.
• Caffeine Content Chart (Coffee, Tea, Soda) — Caffeine content chart: how much caffeine in coffee, espresso, tea, cola, energy drinks and chocolate (mg per serving).

Date & Time

• Military Time Chart (24-Hour Clock Conversion) — Military time chart: 24-hour clock to 12-hour AM/PM conversion for every hour. 13:00 = 1 PM, 23:00 = 11 PM.
• Military Time Zones (Zulu Time & Letters) — Military time zone letters: Zulu (Z) is UTC, Alpha to Mike go east, November to Yankee go west. NATO phonetic time zone reference.
• Time Zones List — UTC Offsets & Cities — Time zones reference: UTC offsets from UTC-12 to UTC+14 with example cities (PST, EST, GMT, CET, IST, JST and more).
• Time Unit Conversions — Seconds, Minutes, Hours, Days — Time conversion chart: seconds, minutes and hours in a minute, hour, day, week, month and year. Quick time unit reference.
• Leap Years List (2000–2100) — List of leap years from 2000 to 2100, with the leap year rule. A leap year has 366 days and a February 29.
• Days in Each Month Chart — How many days in each month: January 31, February 28/29, and the rest. Days per month chart with a handy mnemonic.

Math

• Multiplication Table (1–12) — Printable Times Table — Free printable multiplication table from 1 to 12. Full 12x12 times table chart to learn and reference multiplication facts.
• Squares and Cubes Table (1–50) — Squares and cubes table: n, n squared and n cubed from 1 to 50. Perfect squares and cubes reference for math.
• Square Root Table (1–100) — Square root table for numbers 1 to 100, with exact roots for perfect squares and 5-decimal values for the rest.
• Factorial Table (0! to 20!) — Factorial table listing n! from 0 to 20. 5! = 120, 10! = 3,628,800. Definition and values for factorials.
• Trig Table — sin, cos, tan Values — Trigonometry table of sin, cos and tan for common angles (0, 30, 45, 60, 90 degrees) in degrees and radians, with exact and decimal values.
• Unit Circle Chart — Radians, Sin & Cos — Unit circle chart with angles in degrees and radians and their (cos, sin) coordinates. Exact values for 0, 30, 45, 60, 90 degrees and beyond.
• Log Table — Base-10 Logarithms (1–100) — Logarithm table of base-10 logs (log10) for numbers 1 to 100, to four decimal places. Common log table for math and science.
• Geometry Formulas — Area, Perimeter & Volume — Geometry formulas cheat sheet: area, perimeter and volume for squares, rectangles, triangles, circles, spheres, cylinders, cones and more.
• Algebra Formulas Cheat Sheet — Algebra formulas: quadratic formula, slope, distance, midpoint, exponent rules, logarithm rules and factoring identities. Quick algebra reference.
• Divisibility Rules (2, 3, 4, 5, 6, 9, 10, 11) — Divisibility rules cheat sheet: quick tests to tell if a number is divisible by 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.
• Roman Numerals Chart (1–1000 + Years) — Roman numerals chart from 1 to 1000 with rules and common years. Convert and read Roman numerals: I, V, X, L, C, D, M.
• Prime Numbers List (1 to 1000) — Complete list of prime numbers from 1 to 1000, with the definition and how to test whether a number is prime. 2, 3, 5, 7, 11, 13 and more.
• Fibonacci Sequence — First 50 Numbers — The Fibonacci sequence first 50 numbers (0, 1, 1, 2, 3, 5, 8, 13…), with the rule and link to the golden ratio.
• Pythagorean Triples List — List of Pythagorean triples (a² + b² = c²): 3-4-5, 5-12-13, 8-15-17 and more primitive right-triangle side lengths.
• Fraction to Decimal Chart — Fraction to decimal conversion chart for common fractions: halves, quarters, eighths, sixteenths, thirds and fifths. Divide numerator by denominator.
• Numbers in Words (1 to 100) — Numbers 1 to 100 written in words (English): one, two, three up to one hundred. Spelling reference for writing numbers.
• Pi Digits — First 100 Digits of π — The first 100 digits of pi (π): 3.14159265358979… A reference list of pi decimal places with a short explanation.
• Powers of 10 Table — Powers of 10 table from 10^-12 to 10^12 with values and names (thousand, million, billion, trillion). Scientific notation reference.
• Math Symbols List — Names & Meanings — Math symbols list with names and meanings: + − × ÷ = ≠ ≤ ≥ ± √ ∑ ∫ ∞ π ∈ ∪ ∩ and more mathematical notation.

Science & Nature

• Periodic Table — List of All 118 Elements — Complete list of all 118 chemical elements with atomic number, symbol and name — the full periodic table in order from Hydrogen to Oganesson.
• Periodic Table Groups (Element Families) — Periodic table groups and families: alkali metals, alkaline earth metals, transition metals, halogens, noble gases, lanthanides and actinides.
• Planets of the Solar System (In Order) — The 8 planets of the solar system in order from the Sun, with diameter, distance, number of moons and orbital period. Mercury to Neptune.
• Physics Formulas Cheat Sheet — Physics formulas: speed, acceleration, force (F=ma), kinetic and potential energy, work, power, density, pressure and Ohm’s law.
• Vitamins Chart — Functions & Food Sources — Vitamins chart: vitamins A, B, C, D, E, K — what each does in the body and the best food sources. Quick nutrition reference.
• Beaufort Wind Scale (0–12) Chart — Beaufort wind scale chart: forces 0 to 12 from calm to hurricane, with wind speed in km/h and effects on land.
• Richter Scale — Earthquake Magnitude Chart — Richter scale earthquake magnitude chart: micro, minor, light, moderate, strong, major and great quakes with their effects.
• Resistor Color Code Chart — Resistor color code chart: band colours to digits, multiplier and tolerance. Decode 4-band and 5-band resistors. Brown-Black-Red = 1 kΩ.

Everyday & Life

• List of 50 US States — Abbreviations & Capitals — List of all 50 US states with two-letter abbreviations and capital cities, alphabetical. State codes like CA, TX, NY and their capitals.
• Blood Type Compatibility Chart (Donor & Recipient) — Blood type compatibility chart: who each blood type can donate to and receive from. O− universal donor, AB+ universal recipient.
• Blood Pressure Chart by Category — Blood pressure chart: normal, elevated, hypertension stage 1 and 2, and crisis ranges (systolic/diastolic in mmHg). AHA categories.
• Heart Rate Zones Chart (% of Max HR) — Heart rate training zones chart: zones 1-5 as a percentage of max heart rate (220 minus age) with the benefit of each zone.
• Birthstones by Month Chart — Birthstones by month: the gemstone for each month — Garnet (January), Amethyst (February), Diamond (April), Ruby (July) and more.
• Wedding Anniversary Gifts by Year — Wedding anniversary gifts by year: traditional materials from paper (1st) and wood (5th) to silver (25th), gold (50th) and diamond (60th).
• Chinese Zodiac Years Chart (Animals by Year) — Chinese zodiac years chart: the 12 animals (Rat, Ox, Tiger, Dragon…) and their birth years. Find your Chinese zodiac sign by year.
• Generations by Birth Year (Gen Z, Millennials…) — Generations by birth year chart: Silent Generation, Baby Boomers, Gen X, Millennials, Gen Z and Gen Alpha with their year ranges.
• Recycling Symbols — Plastic Codes 1–7 — Recycling symbols explained: plastic resin codes 1 to 7 (PET, HDPE, PVC, LDPE, PP, PS, Other) and which plastics are recyclable.
• Laundry Symbols Guide — Care Label Meanings — Laundry care symbols explained: wash, bleach, tumble dry, iron and dry-clean symbols on clothing labels and what the dots mean.
• Dog Years to Human Years Chart — Dog years to human years chart: convert your dog’s age to equivalent human years. 1 dog year ≈ 15 human years.
• Greek and Roman Gods (Names & Equivalents) — Greek and Roman gods chart: Zeus/Jupiter, Poseidon/Neptune, Athena/Minerva and more — equivalent names and what each god rules.
• Scrabble Letter Values Chart — Scrabble letter values: points for every tile in English Scrabble. A/E/I/O/U=1, D/G=2, B/C/M/P=3, K=5, Q/Z=10 and blanks=0.
• Chess Notation Guide (Algebraic) — Chess algebraic notation explained: piece letters (K, Q, R, B, N), captures (x), check (+), checkmate (#), castling and promotion.
• Music Note Values Chart — Music note values chart: whole, half, quarter, eighth and sixteenth notes and how many beats each lasts in 4/4 time.

Language & Symbols

• Greek Alphabet — Letters, Names & Symbols — The Greek alphabet chart: all 24 letters (Alpha to Omega) with uppercase, lowercase, names and Latin equivalents. For math, science and fraternities.
• Cyrillic Alphabet Chart (Russian) — 33 Letters — Cyrillic (Russian) alphabet chart: all 33 letters with upper and lower case and Latin transliteration.
• Currency Symbols List — Codes & Names — World currency symbols reference with ISO codes and names: dollar, euro, pound, yen, rupee, won and more. Copy currency symbols for any region.
• Currency Codes List (ISO 4217) — ISO 4217 currency codes list: USD, EUR, GBP, JPY, CNY, INR and more with currency names and symbols.
• Language Codes List (ISO 639-1) — ISO 639-1 language codes: two-letter codes for English (en), Spanish (es), French (fr), Chinese (zh) and more world languages.
• Keyboard Symbol Names — What Symbols Are Called — Keyboard symbol names reference: what each symbol is called — hash #, ampersand &, caret ^, tilde ~, asterisk *, pipe | and more punctuation names.
• Math Symbols List — Names & Meanings — Math symbols list with names and meanings: + − × ÷ = ≠ ≤ ≥ ± √ ∑ ∫ ∞ π ∈ ∪ ∩ and more mathematical notation.
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