Percentage Calculator
Percentage Calculator works out percentages and percentage change, free and in your browser. It answers three common questions: what is a percentage of a number, what percentage one number is of another, and how much a number has changed in percentage terms.
Last updated: 30 October 2026 · Free · No signup
Percentages are used everywhere: discounts, marks, interest, tax, and growth figures. The arithmetic is simple in principle, but it is easy to mix up which number is the base, especially for percentage change. This tool keeps the three calculations separate, so you enter the numbers for the question you actually have, rather than trying to adapt one formula to all three.
For percentage change, be clear about the starting number, because the change is always measured against where you started. A rise from 50 to 75 is a 50 percent increase, but a fall from 75 to 50 is only a 33 percent decrease, even though the absolute change is 25 in both cases.
Privacy: this tool runs entirely in your browser — no upload, no signup, and your files never leave your device.
The three most useful percentage calculations in one place — a percentage of a number, one number as a percentage of another, and percentage change.
1) What percentage of a number?
2) One number as a percentage of another?
3) Percentage change (increase / decrease)
How to use Percentage Calculator
- Choose which percentage calculation you need.
- Enter the numbers.
- Read the result.
- Use it in your price, mark, or growth calculation.
Key facts
| Calculations | A percentage of a number, a number as a percentage, and percentage change |
|---|---|
| Input | The numbers for the calculation you need |
| Upload | None — calculation happens in your browser |
Frequently asked questions
How do I work out what 20% of 250 is?
Multiply 250 by 20 and divide by 100, which gives 50. In this tool, enter 20 as the percentage and 250 as the number, and the result will show straight away.
How do I work out percentage change?
Subtract the old number from the new number, divide by the old number, and multiply by 100. The tool does this for you, but the key point is that the old number is always the base, so a rise and a fall by the same amount give different percentages.
What is the difference between percent and percentage points?
Percent is a relative change, while percentage points are the simple difference between two percentages. Going from 20% to 25% is a rise of 5 percentage points, but a 25% relative increase, because 5 is a quarter of 20.
Are my percentage numbers uploaded or saved?
No. Calculation happens in your browser only. Nothing is sent to a server and nothing is saved after you close the page.