Percentage Calculator
Calculate percentages, increases, and decreases.
Use on any page (bookmarklet)
Want Percentage Calculator without leaving the page you're on? Drag the button below to your bookmarks bar, then click it on any website to open Percentage Calculator right there — it runs entirely in your browser.
Use responsibly: a bookmarklet runs on whatever page you click it on. Avoid sensitive sites such as online banking, payment, or healthcare pages — you run it at your own risk. Everything is processed locally and no data is sent anywhere. See our Terms.
- Show your bookmarks bar if it's hidden — Ctrl+Shift+B (⌘+Shift+B on Mac).
- Drag the button above onto the bookmarks bar.
- Open any website and click the bookmark — the Percentage Calculator panel appears in the top-right corner. Use ✛ to move it between corners, or ›/‹ to tuck it against the edge and pull it back out.
- Click the bookmark again (or the ✕) to close it.
Note: a few sites with strict security policies may block bookmarklets.
Examples
Percent of a number
Input
15% of 200
Output
30
What percent is X of Y
Input
30 of 200
Output
15%
Percentage change
Input
200 → 250
Output
+25%
About this tool
This free online percentage calculator handles the three calculations you reach for most: what is X% of a number, what percent one number is of another, and the percentage increase or decrease between two numbers. Everything updates live and runs in your browser with no upload.
How to use
- Pick the calculator that matches your question.
- Type the numbers — results update instantly as you type.
- Use decimals or negatives freely.
Everyday percentage problems
Use it for discounts and sale prices, tips, tax, test scores, commission, and tracking growth or decline month over month. For shopping discounts specifically, the related Discount Calculator shows the final price and savings directly.
Frequently asked questions
Is this percentage calculator free?
Yes — it's a completely free online percentage calculator with no sign-up.
Is anything sent to a server?
No. All calculations run in your browser with no upload — nothing you enter leaves your device.
How do I find X% of a number?
Use the first calculator: enter the percentage and the number. For example, 15% of 200 is 30.
How do I find what percent one number is of another?
Use the second calculator: enter the part and the whole. For example, 30 is 15% of 200.
How do I calculate percentage increase or decrease?
Use the third calculator: enter the original and new values. Going from 200 to 250 is a +25% change; a negative result means a decrease.
How is percentage change calculated?
Percentage change = (new − old) ÷ old × 100. So from 80 to 60 is (60 − 80) ÷ 80 × 100 = −25%.
Can I use decimals?
Yes. Enter any numbers, including decimals and negatives, and results update live.
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