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How to Calculate Percent Change

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Direct answer

Percent change is the signed difference relative to an initial value. The order matters because the initial value supplies the denominator.

Formula and method

((new − old) ÷ old) × 100

This page must show the formula exactly as the calculator or worked method uses it. Inputs remain unrounded during the calculation; rounding applies only to the displayed answer unless a domain-specific rule requires otherwise.

Step-by-step calculation

  1. Label old and new before calculating.
  2. Subtract old from new.
  3. Divide by old.
  4. Convert the ratio to a percentage and attach direction.

Worked examples

Sales

$42,000 to $48,300: 6,300 ÷ 42,000 = 15%.

Response time

250 ms to 190 ms: −60 ÷ 250 = −24%.

More than doubles

40 to 100: 60 ÷ 40 = 150%.

Interpretation and edge cases

  • Use comparable periods and definitions.
  • Do not switch the order to force a positive result.
  • When old is zero, report the absolute change and explain that the percent is undefined.

Frequently asked questions

Which number goes on the bottom?

The initial or old value.

Why does swapping values change the answer?

The denominator changes.

Should decreases be negative?

Signed percent change is negative; a percentage-decrease page may report the magnitude as positive.

Sources and transparency

The formulas and examples were evidence-checked on 2026-09-10. This is educational mathematical content. It does not replace a field-specific standard, accounting policy, laboratory method, contractual definition or professional judgment. CalculatorGeek should display a named human reviewer only after a real reviewer has completed and documented that review.

Use this resource

1 available tool
Open the Percent Change CalculatorRun the calculation with your own inputs, then return here to interpret it.

Keep exploring

4 available tools
Percent Increase vs Percent DecreaseCompare percent increase and percent decrease formulas, direction, baselines and recovery effects with worked examples.Percent Change With Zero or Negative ValuesUnderstand percent change when the starting value is zero or negative. Compare denominator conventions and learn when an absolute change is safer.Percentage Points vs Percent ChangeLearn the difference between percentage-point change and percent change with rates, survey results and conversion examples.Compound Percent ChangeCombine multiple percentage increases and decreases with growth factors. Calculate total change without adding the rates.