Wyvek

Percentage Calculator

Work out percentages, increases & differences.

What is X% of Y?

of
Result —

X is what percent of Y?

of
Result —

Percentage increase or decrease

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Change —

Free online percentage calculator

This percentage calculator packs three common calculations into one page so you never have to reach for a formula. Work out what a percentage of a number is, find out what percent one number is of another, and measure a percentage increase or decrease between two values. Every field is live — the moment you type, the answer appears — and everything runs privately in your browser with no sign-up and no data leaving your device.

How to calculate a percentage

  1. Pick the calculator that matches your question: percentage of a value, a part as a percent of a whole, or the change between two numbers.
  2. Type your numbers into the two fields — decimals and negatives are fine.
  3. Read the result instantly; it is rounded neatly with trailing zeros trimmed.
  4. Click Copy to send any answer to your clipboard.

Everyday uses for percentages

Percentages turn up everywhere: working out a store discount or sales tax, calculating a tip, checking a test score, comparing this month's revenue to last month's, or figuring out how much a price rose. The increase/decrease calculator is especially handy for spotting growth and drops at a glance, showing a clear increase or decrease label with the signed percentage.

Private, accurate, and free

All arithmetic happens locally in JavaScript, so your figures stay on your machine. Need to crunch other numbers? Estimate repayments with our loan calculator, or check your BMI in metric or imperial units. Bookmark this page so the next percentage is only a click away.

Frequently asked questions

How do I calculate a percentage of a number?

To find X% of a number Y, multiply Y by X and divide by 100. For example, 20% of 150 is 150 × 20 ÷ 100 = 30. The first calculator on this page does it for you — just enter the percentage and the value and the answer updates instantly.

How do I work out what percent one number is of another?

Divide the part by the whole and multiply by 100. For example, 30 out of 150 is 30 ÷ 150 × 100 = 20%. Use the second calculator above and enter the part and the whole to get the percentage.

How do I calculate percentage increase or decrease?

Subtract the original (from) value from the new (to) value, divide by the original value, and multiply by 100. A positive result is an increase and a negative result is a decrease. For example, going from 80 to 100 is (100 − 80) ÷ 80 × 100 = a 25% increase.

What happens if I divide by zero?

Percentages that require dividing by zero — such as "X is what percent of 0" or a change from an original value of 0 — are mathematically undefined. This calculator detects those cases and shows a friendly message instead of an error or NaN.

Is this percentage calculator free and private?

Yes. Every calculation runs entirely in your browser with JavaScript, so nothing you type is uploaded or stored. It is completely free, needs no sign-up, and works offline once the page has loaded.

How are the results rounded?

Results are rounded to a few decimal places and any trailing zeros are trimmed, so a clean whole number stays whole (30, not 30.00) while a repeating value like 33.3333% is shown to a sensible precision.

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