Free browser tool
Percentage Calculator
Calculate part-of-total percentages, percent increases, percent decreases, and percent change with examples, reset controls, and copyable summaries.
Updated 2026-05-18
Examples
Choose a calculation to see the result.
Percent change uses the old value as the base. That is different from percentage points, which compare two percentages directly.
How to use this tool
- Paste or type your input into the tool.
- Choose the action or option that matches your task.
- Review the output before copying it into another app.
Notes
Run common percentage calculations from presets or custom values, then copy a readable result that shows the inputs, output, and percent-change base.
Inputs are processed in the browser for this static MVP. Avoid pasting secrets into any online tool unless you understand the environment.
FAQ
What percentage calculations are included?
It handles part-of-total percentages, increase or decrease by a percentage, and percent change between old and new values with copyable summaries.
Does it round the result?
Results use compact rounding when needed, so everyday calculations stay readable while still showing the original values in the copyable output.
What is the main percent change mistake?
The old value is the base for percent change. If you are comparing two percentages directly, you probably need percentage points instead.
Can I use the presets as examples?
Yes. The preset buttons fill common discount, ratio, increase, and decrease examples so you can see which input fields belong together.