Calculate& Decide

Everyday Math calculator

Percentage Change Calculator

This calculator compares the difference with the original value and identifies an increase, decrease, or no change.

Updated · Inputs stay in your browser

Enter your values

The nonzero baseline.
The comparison value.

Your values stay on this device. Nothing is sent to Calculate & Decide unless you deliberately use your device's share feature.

What this result means

This calculator compares the difference with the original value and identifies an increase, decrease, or no change. The results panel explains the main number and the quantities that produced it, so you can check whether the estimate answers your real question.

Formula used

Percentage change = (New value − Original value) ÷ |Original value| × 100.

Step-by-step calculation

  1. Validate every required value and reject values outside the stated field limits.
  2. Convert rates and time periods to the units required by the formula.
  3. Calculate with full JavaScript number precision; do not round intermediate values.
  4. Round only the displayed result and explain the practical meaning.

Worked example

A value rising from 80 to 100 changes by 20, which is a 25% increase relative to 80.

Assumptions and limitations

  • The original value is not zero.
  • Both values describe the same quantity and units.
  • The original value is the comparison baseline.

How to use this calculator

  1. Choose a currency symbol when the tool uses money.
  2. Enter values in the units shown beside each field.
  3. Select Calculate, then read both the main result and interpretation.
  4. Change one uncertain input at a time to understand sensitivity.
  5. Use Copy result or Share only when you choose to move the result outside this page.

Common mistakes

  • Dividing by the new value instead of the original.
  • Confusing percentage change with percentage-point change.
  • Comparing values measured over different periods.

Frequently asked questions

Why can the original value not be zero?

Percentage change needs a nonzero baseline.

Can values be negative?

Yes, but interpretation requires care when signs change.

What is no change?

Equal values produce 0%.

Methodology and sources

Formula definitions and edge-case behavior are documented on our Methodology page. No external data is fetched by this calculator.

See the site-wide calculation methodology and editorial standards. Formula errors can be reported through the error-reporting instructions.

Published and reviewed .