Percentage Calculator

Percentage questions come in more than one shape — finding a discount amount, checking what share of a budget was spent, or measuring how much a number grew or shrank — and each shape needs the numbers plugged in differently. This calculator handles three common percentage calculations in one tool, with a mode switch so you don't need to remember which formula applies to which situation.

What each mode calculates

"X% of Y" answers questions like "what is 20% of 500?" — useful for calculating a discount, tip, or commission amount. "X is what % of Y" answers "50 out of 200 is what percentage?" — useful for figuring out test scores, budget shares, or completion rates. "% change from X to Y" answers "a price went from 80 to 100 — what percent did it increase?" — useful for tracking growth, price changes, or performance shifts over time.

Everyday situations these modes solve

Working out a restaurant tip or a sales discount using the "X% of Y" mode. Checking what percentage of a total budget a specific expense represents using "X is what % of Y." Comparing this month's sales figures to last month's, or this year's rent to last year's, using the "% change" mode to see the exact growth or decline rate.

Frequently Asked Questions

Can the change mode show a negative percentage? The result always shows a positive number labeled either "increase" or "decrease" depending on whether the new value is higher or lower than the original, so the direction is clear without needing to interpret a negative sign.

Does it handle decimal numbers? Yes — all three modes accept decimal values for more precise calculations, not just whole numbers.

Is my data saved anywhere? No — every calculation runs locally in your browser using JavaScript; nothing is stored or transmitted.