➗ Math

Percentage Change Calculator

Calculate the percentage increase or decrease from an old value to a new value.

Results

Percentage change
25.0000%
Direction
Increase
Absolute change
20

📊 Percentage Change Calculator chart

Visual summary of your results.

What is the Percentage Change Calculator?

Calculate the percentage increase or decrease from an old value to a new value. From percentages and fractions to logarithms and quadratic equations, these math calculators show exact results — using arbitrary-precision integers wherever whole-number answers can get very large.

Percentage Change Calculator – free online math tool illustration
Percentage Change Calculator — free, exact and private.

How to use the Percentage Change Calculator

  1. Enter your old value, your new value.
  2. Results update automatically as you type; you can also press Calculate.
  3. Read the output: percentage change, direction, absolute change.
  4. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

Change % = (New − Old) ÷ |Old| × 100

Worked example

With old value = 80, new value = 100, the Percentage Change Calculator returns percentage change: 25.0000%; direction: Increase; absolute change: 20.

Tips for better results

  • Use the formula section on each page to check your homework method, not just the answer.
  • For very large factorials, combinations and base conversions we use exact big-integer math.
  • Floating-point results are rounded to 12 significant digits to remove binary noise.

Frequently asked questions

What does the Percentage Change Calculator do?

Calculate the percentage increase or decrease from an old value to a new value.

How is it calculated?

The Percentage Change Calculator uses this method: Change % = (New − Old) ÷ |Old| × 100.

Can you show an example?

With old value = 80, new value = 100, the Percentage Change Calculator returns percentage change: 25.0000%; direction: Increase; absolute change: 20.

Is the Percentage Change Calculator accurate?

Yes. It uses standard formulas and exact constants, and the results are verified by our automated test suite. Values are displayed to up to 12 significant digits.

Is this tool free and private?

Yes — the Percentage Change Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.

Related tools

Percentage Increase CalculatorIncrease a number by a given percentage.Percentage Decrease CalculatorDecrease a number by a given percentage.Percent Difference CalculatorCalculate the percent difference between two values relative to their average.Percent Error CalculatorCalculate percent error between a measured (experimental) value and the true value.Fraction to Decimal CalculatorConvert any fraction or mixed number to a decimal and a percentage.Decimal to Fraction CalculatorConvert a decimal number to its simplest fraction and mixed number.Fraction CalculatorAdd, subtract, multiply or divide two fractions and get a simplified answer.Ratio CalculatorSimplify a ratio and scale it to a new total or term.

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