How do I calculate percent increase?

Use the % Increase/Decrease tab, enter the original and new value, and the tool shows the percent change.

What is a reverse percentage?

It finds the original number when you know a result and what percent that result represents.

Is my data sent anywhere?

No, every calculation happens locally in your browser.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

Percentage Calculator

Calculate X% of Y, percent change, and reverse percentages.

Support

Works Offline

Privacy First

No Login

No API

Percentage Calculator

Choose a calculation mode

Percentage (%)

Of value (Y)

20% of 150 is:

Result

Updates live as you type

20% of 150

What percent

25%

Difference

Percent change

+25% (increase)

Original number

250

About the Percentage Calculator

A complete percentage toolkit: find what X% of a number is, work out what percent one number is of another, calculate percent increase or decrease, and reverse-engineer an original value from a percentage result.

Examples

20% of 150

20% of 150

Output

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser