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Math formula

How to calculate percentage change

Percentage change measures how much a value rose or fell compared with where it started.

See the formulaOpen calculator
Direct answer
Formula
percentage change = (new value - original value) / abs(original value) * 100

Use the table below to match each symbol with the right input. Keep units consistent before you start.

Percentage change formula
Start here when you only need the equation and variable names.
Formula
percentage change = (new value - original value) / abs(original value) * 100

Percentage change measures how much a value rose or fell compared with where it started.

Variable meanings
Check each symbol, meaning, and unit before you calculate.
SymbolNameDescriptionUnit
new valueNew valueEnding measurement.Depends on inputs
original valueOriginal valueStarting measurement.Depends on inputs
When to use this formula
Check that your situation matches the formula before you trust the result.
  • Good for price changes, score changes, traffic changes, and before-after comparisons.
Step-by-step method
Follow these steps when you are solving it by hand.
  1. 1Subtract original value from new value.
  2. 2Divide by the absolute value of the original.
  3. 3Multiply by 100.
  4. 4Use a positive sign for an increase and a negative sign for a decrease.
Examples
These sample numbers show the order of operations and units.
Increase
original value
80
new value
92
  1. 1.percentage change = (92 - 80) / 80 * 100
  2. 2.percentage change = 12 / 80 * 100
  3. 3.percentage change = 15%
Result
The value increased by 15%.
Decrease
original value
150
new value
120
  1. 1.percentage change = (120 - 150) / 150 * 100
  2. 2.percentage change = -30 / 150 * 100
  3. 3.percentage change = -20%
Result
The value decreased by 20%.
Mistakes to avoid
Small input or unit errors can change the answer a lot.
  • Putting the wrong value in the numerator or denominator of the percentage change formula.
  • Skipping signs, order, or sorting rules that change the result.
  • Rounding before the last step.
  • Assuming a formula applies when the needed input is zero or missing.
Open the Percentage Change Calculator
Open the calculator for the answer without rewriting the formula.

Enter your values in the related calculator, then compare the output with the hand method above.

Open Percentage Change Calculator
FAQs
Short answers for common formula questions.
Can I calculate Percentage change by hand?

Yes. Write the units next to each value, convert rates or measurements first, and round only the final answer.

Why does my Percentage change result differ from another calculator?

Most differences come from rounding, unit conversions, rate timing, or a slightly different version of the formula.

When is the Percentage Change Calculator better than hand math?

Open the Percentage Change Calculator to check several scenarios or skip the hand arithmetic.