Percentage change
(100 − 80) ÷ 80 × 100. A negative result is a decrease.
Change = (new − original) ÷ original × 100
Formula
(New − original) ÷ original × 100
How the calculation works
Compare an original value and a new value to find relative change. Enter each measurement in the unit shown beside the input. The result updates when you change a value; incomplete or unsupported inputs display an explanation.
Worked example
A rise from 80 to 100 is 20 ÷ 80 × 100 = 25%.
When to use this calculator
Use this to compare quantities before and after a change.
Common mistakes and limits
A zero starting value has no defined relative percentage change.
Check your result
Check that all measurements describe the same object or time period. Repeat the calculation with unrounded values, then round only the final quantity to a precision suitable for the task.
Frequently asked questions
Does this calculator need an account?
No. Calculations run in your browser without an account.
How precise is the displayed result?
The display rounds to six decimal places. Measurement uncertainty can be larger than this rounding.
