How to use the percent increase and decrease calculator
Compute percent change between two values. Enter old value, new value in the fields above; the percent change, difference are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- a — Old value
- b — New value
Worked example
With old value = 80, new value = 100, the calculator gives percent change ≈ 25 %; difference ≈ 20.
Frequently asked questions
What is the formula for the percent increase and decrease calculation?
Percent change (%) = 100 × (b-a) / a. Difference = b-a. Here a is old value, b is new value.
What inputs do I need for the percent increase and decrease calculator?
You need old value, new value. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.