Percentage Calculator
Three percentage problems in one live tool: X% of Y, X is what percent of Y, and the percent change between two values.
This tool runs entirely in your browser. Your data never leaves your device — it is not uploaded to any server.
How to use
- 1Pick the mode: X% of Y, X is what % of Y, or % change.
- 2Type the two values into the two boxes.
- 3Read the live result — with the direction labeled for changes.
Percentage Calculator
The three questions people actually ask: “what is 15% of 200?”, “30 is what percent of 150?” and “sales went from 480 to 610 — by what percent?”. Switch modes with one click and the formula adapts to each case.
Percent change is signed and labeled as an increase or a decrease, so a drop from 500 to 400 clearly reads as −20%, not a confusing positive number.
Frequently asked questions
How is percent change calculated?
(final − initial) ÷ |initial| × 100. The absolute value in the denominator means a change from −50 to −40 correctly reports +20% rather than −20%. Reverse direction (400 → 500) gives +25% because the base changes.
Why is a 20% rise followed by a 20% fall not zero?
Percentages apply to different bases: 100 + 20% = 120, then 120 − 20% = 96. Net change is −4%. This asymmetry trips up price comparisons and news headlines alike.
Can I use negative or decimal numbers?
Yes. Both inputs accept negatives and decimals, so “−5% of 80” or percentage points on a temperature change work fine.
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Embed this tool
Put this tool on your own site with one line — it runs entirely in the visitor's browser.
<iframe src="https://zoyku.com/en/tools/percentage-calculator?embed=1" width="100%" height="640" style="border:0;border-radius:16px" title="Zoyku — percentage-calculator" loading="lazy"></iframe>