Unit Converter
Convert units of measurement.
OpenCalculate percentages quickly. - runs entirely in your browser. Free, fast and private.
Find X% of Y, percent change, or what percent X is of Y.
Fill the two numbers your scenario provides.
Answer updates instantly with formula shown.
Copy the figure for invoices, grades, or discounts.
Percentage Calculator is a free math & calculators utility on OneDevToolkit. Calculate percentages quickly. It runs in your browser for this session - use the workspace on this page to try it.
Need a related step? Open the Math & Calculators hub at /math-tools/ or the <a href="/blog/">blog</a> for longer workflows.
Processes data instantly with no server round-trips.
Your data never leaves your browser. Nothing is uploaded.
Works in any modern browser. Nothing to download or install.
No limits, no sign-up, no credit card required.
Works on desktop, tablet and mobile devices.
Beautiful in both themes. Your preference is saved.
Keyboard shortcut
Open Percentage Calculator when you need a quick result without uploading data to a third-party site.
No install required - bookmark the tool and return anytime.
Client-side processing keeps inputs on your device for core OneDevToolkit tools.
Answers for this tool. For site-wide help, open the FAQ hub.
Percentage Calculator helps you calculate percentages quickly. instantly in the browser.
Yes - modern browsers handle Unicode strings. Some case transforms behave differently for locale-specific characters.
Most text tools preserve line structure unless the operation is specifically about wrapping, sorting, or joining lines.
No artificial server quota. Extremely large pastes may slow the tab - split the text if needed.
Use Clear and re-paste, or keep the original in another tab. Browser undo may work inside the textarea.
Processing is local. Avoid pasting secrets into any website if your policy forbids it - prefer offline editors for credentials.
Use Copy on the toolbar or select the output panel. Download is available when the tool exposes a file export.
Treat markup as plain text unless the tool is specifically a Markdown/HTML utility. Preview elsewhere if rendering matters.
Paste from Notes/email, run Percentage Calculator, then copy back. Long documents are easier on desktop.
Browse Math & Calculators for case converters, counters, diff, and cleanup tools.