％ Percentage Calculator
To find X% of a number, multiply the number by X ÷ 100 — so 15% of 80 is 80 × 0.15 = 12. Enter your values below — results update instantly, entirely on your device.
80 × 0.15 = 12
15% means 15 per 100
How the percentage calculator works
result = value × (percentage ÷ 100). "Percent" literally means "per hundred" — 15% is 15 parts of every 100.
Example: 15% of 80 → 80 × 0.15 = 12.
Handy reversal: X% of Y always equals Y% of X. Awkward problems flip into easy ones — 8% of 50 is the same as 50% of 8, which is instantly 4.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply: 20% of 250 = 250 × 0.20 = 50.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100: 30 out of 120 = 30 ÷ 120 × 100 = 25%.
What is the fastest mental percentage trick?
Anchor on 10%: move the decimal one place (10% of 340 = 34), then scale — 5% is half of that, 20% is double, 15% is one-and-a-half times. And remember X% of Y = Y% of X.
Is this percentage calculator accurate and private?
Yes. It uses the standard published formula, shows its working under every result, and computes locally in your browser — your inputs are never sent to a server, and the page works offline.