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Percentage Change Calculator

Percentage Change Calculator — get the answer instantly in your browser, free and private.

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About the Percentage Change Calculator

The Percentage Change Calculator determines the percentage increase or decrease between two values—showing how much something has grown or shrunk as a percentage. This free, browser-based tool calculates the exact percentage change from an old value to a new value instantly, making it essential for financial analysis, scientific calculations, business reporting, and everyday comparisons. Because it runs entirely in your browser with no sign-up required, your data stays private and calculations happen instantly.

How Percentage Change works

The percentage change formula is:

[(New Value - Original Value) / |Original Value|] × 100 = Percentage Change

How it works:

  1. Enter your original (starting) value
  2. Enter your new (final) value
  3. The calculator subtracts the original from the new value
  4. Divides that difference by the absolute value of the original
  5. Multiplies by 100 to get a percentage

A positive result means an increase; a negative result means a decrease.

Worked Example:

Suppose a product's price increased from to 0.

  • New Value: 0
  • Original Value:
  • Difference: 0 - =
  • Divide by original: / = 0.5
  • Multiply by 100: 0.5 × 100 = 50%

The price increased by 50%.

Another example with a decrease: If sales dropped from 500 units to 350 units:

  • Difference: 350 - 500 = -150
  • Divide by original: -150 / 500 = -0.3
  • Multiply by 100: -0.3 × 100 = -30%

Sales decreased by 30%.

How to use

  1. Enter your values as shown in the input box.
  2. The result is calculated instantly.
  3. Click Copy to use it.

Common uses

  • Finance: Calculate returns on investments, compare stock prices, or analyze salary changes year-over-year
  • Business: Track revenue growth, measure customer acquisition changes, or monitor expense fluctuations quarter-to-quarter
  • Retail: Determine discount percentages during sales, or calculate markup percentages when pricing products
  • Chemistry and Physics: Measure experimental error rates, compare observed vs theoretical results, or track changes in measurements
  • Education: Evaluate student performance improvements, compare test score changes, or analyze enrollment growth
  • Personal Finance: Track changes in savings goals, weight loss/gain percentages, or utility bill increases

Frequently asked questions

What's the difference between percentage change and percent difference?
Percentage change measures change from an original value to a new value (always in one direction), while percent difference treats both values as equal and measures the gap between them symmetrically.
Can the calculator handle negative numbers?
Yes. The formula uses the absolute value of the original number, so it works correctly with both positive and negative starting values.
What if my original value is zero?
The calculator cannot compute percentage change when the original value is zero because division by zero is undefined mathematically. You need a non-zero starting point.
Why do I get a negative percentage?
A negative percentage means a decrease. For example, -20% means the value dropped to 80% of its original amount.
Does this tool store my calculations?
No. The tool runs entirely in your browser without uploading any data to our servers. Your calculations are private and processed locally.
How accurate are the results?
The calculator is accurate to many decimal places and follows standard mathematical principles. All results are mathematically correct for the formula used.