Percentage Change Calculator

How to use the Percentage Change Calculator

Compare an original value with a new value to find the relative percentage increase or decrease.

Measure relative increase or decrease from an original value to a new value. The denominator is always the original value, which distinguishes percentage change from percentage-point difference.

Fieldlet calculates locally and shows a practical estimate. Confirm consequential financial, contractual, health, or compliance decisions with an authoritative source.

1. Subtract the starting value from the new value.
2. Divide the difference by the absolute starting value.
3. Multiply by 100 to express the change as a percentage.

Last reviewed for accuracy: 2026-08-31

Worked examples

How the result is produced

Fieldlet subtracts original from new, divides the difference by the absolute original value, and converts to percent. The sign indicates direction: positive for increase and negative for decrease.

• Change = new − original
• Percentage change = change ÷ |original| × 100
• A change from 40% to 50% is 10 percentage points but a 25% relative increase

Choose the baseline before interpreting the result

Percentage change is directional because the original value is the denominator. Moving from 80 to 100 is a 25% increase, while moving from 100 back to 80 is a 20% decrease; the absolute difference is the same, but the baselines are not.

• Use the earlier or reference value as the starting value.
• Do not confuse percentage change with percentage-point change.
• State the baseline when presenting the result.

Limitations and common mistakes

• Percentage change from an original value of zero is undefined.
• Negative starting values require context because ordinary increase/decrease language can become misleading.

Common questions