Free Online Percentage Calculator
A percentage calculator solves three modes: X% of Y, X as a percent of Y, and the percent change from X to Y.
Your data is processed entirely in your browser and never sent to any server.
How to Use This Calculator
- Pick the mode tab: "X% of Y", "X is what % of Y", or "% change".
- Enter the two numbers in the labelled fields.
- The answer and the formula used appear live under the inputs.
- Adjust decimal precision to taste, then copy the result.
What Is a Percentage Calculator?
The three standard percent problems each have a one-line formula. "What is X% of Y" is X ÷ 100 × Y. "What percent is X of Y" is X ÷ Y × 100. "What's the percent change from X to Y" is (Y − X) ÷ X × 100. Mixing them up is the most common percent error in finance reports and homework.
Students reach for this when checking a graded quiz; shoppers when sanity-checking a discount; analysts when reading sales decks. Each mode runs the exact arithmetic and prints the working (e.g. `15 ÷ 100 × 84.50 = 12.675`), so you can copy the figure into a report and justify it later.
Decimal precision is configurable. Everything runs locally — the numbers you type never leave the browser, useful when the values are commercially sensitive.
Frequently Asked Questions
How do I calculate percentage of a number?
What is percentage change?
Can I use this calculator for discounts?
Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.
Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.