Percentage Change Calculator

Calculate an increase or decrease

Enter the original amount and the new amount in the same units. The original value must be positive. Select Calculate to see the relative increase or decrease; equal values produce no change. Negative new values are allowed, but a negative original value is not supported because the usual increase/decrease labels become ambiguous.

Formula: (new value − original value) ÷ original value × 100. The answer is rounded to two decimal places. A positive answer is an increase; a negative answer is a decrease. This is a comparison of two values, not a forecast.

Worked examples

A price rises from 80 to 100

The change is 20. Divide 20 by the original 80, then multiply by 100: the increase is 25%. Use the original amount as the denominator, not the new amount.

A count falls from 250 to 200

The change is −50. Dividing by 250 and multiplying by 100 gives −20%, shown as a 20% decrease. Reversing the journey from 200 to 250 is a 25% increase because the starting amount is different.

The new amount is zero

Going from 60 to zero is a 100% decrease. Going from zero to 60 has no finite percentage increase under this formula; report the absolute increase instead.

Percentage change versus percentage points

If a rate moves from 20% to 25%, it rises by 5 percentage points. Relative to the starting rate, it increases by 25%: (25 − 20) ÷ 20 × 100. State which measure you use so readers do not confuse a five-point difference with five-percent growth.

For a share of a total, use the percentage tool on our math calculators page. For adding rational numbers, use the fraction calculator.

Limits and review

Inputs must be finite numbers. Extremely large results are rejected rather than displayed as infinity. Values close enough to zero may round to 0.00%; inspect the original numbers if that difference matters. Results are computed locally, and entering new numbers clears the previous answer.

Reviewed September 15, 2026. Methods and corrections.