Percentage Calculator
Calculate percentages, ratios, and percentage change.
100% client-side — your data never leaves your browser.
Enter both values to see your result.
About the Percentage Calculator
A clean, three-in-one percentage calculator. Find a percentage of any number, work out what percentage one number is of another, or measure the percentage change between two values — with instant results as you type.
How to use the Percentage Calculator
- 1Pick the calculation mode that matches your question.
- 2Enter your two numbers into the input fields.
- 3Read the answer instantly — no "Calculate" button needed.
- 4Switch modes to run another calculation right away.
Why use our Percentage Calculator
Three modes
X% of Y, X is what % of Y, and percentage change — covers every common question.
Instant results
Answers update live as you type, with sensible decimal formatting.
Handles negatives
Percentage change works correctly for both increases and decreases.
Private & free
Everything is calculated locally in your browser — no sign-up, no tracking.
Frequently asked questions
How do you calculate percentage change?+
Percentage change = (new − old) ÷ |old| × 100. A positive result is an increase, a negative result is a decrease. We use the absolute value of the original number so the sign reflects direction correctly.
What does "X is what % of Y" mean?+
It tells you what proportion X is of Y. For example, 25 is 50% of 50, because 25 ÷ 50 = 0.5.
Why does the result show several decimals?+
We show up to four decimal places to stay precise. Round the result yourself if you need a cleaner number for your context.
Is anything I type stored or uploaded?+
No. All math happens in your browser — your inputs never leave your device.