% Percentage Calculator

Work out any percentage — of a number, the percent one value is of another, an increase or decrease, or adding and subtracting a percent. Instant, with the formula shown.

Result3015% of 200 is 3015% × 200 = 30

One Calculator, Every Percentage Question

The four calculations people search for most — without hunting for a separate tool each time.

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Every Mode

Percent of a number, what-percent-of, increase/decrease and add/subtract — all in one place.

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Instant Results

Answers update the moment you type — no submit button, no page reloads.

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Formula Shown

See the exact working behind every answer, so you learn the method, not just the number.

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Private & Free

Runs entirely in your browser — no login, no limits, dark mode and fully responsive.

How to Use the Percentage Calculator

Four steps — results update the moment you type.

1

Pick a mode

Choose what you're calculating: percent of a number, what-percent, change, or add/subtract.

2

Enter your numbers

Type the two values into the boxes — the result updates live as you type.

3

Read the answer

See the result, a plain-English sentence and the formula used to get it.

4

Reuse it

Switch modes anytime to answer a different percentage question with the same numbers.

Frequently Asked Questions

How to calculate percentages, percentage change, increases, decreases and discounts.

How do I calculate a percentage of a number?

To find X% of a number, divide the percent by 100 and multiply by the number. For example, 15% of 200 = (15 ÷ 100) × 200 = 30. Use the '% of a number' mode above and it does this instantly, showing the formula.

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

Divide the part by the whole and multiply by 100. For example, 30 out of 200 = (30 ÷ 200) × 100 = 15%. The 'X is what % of Y' mode calculates this for you.

How do I calculate percentage increase or decrease?

Subtract the original value from the new value, divide by the original, and multiply by 100. Going from 200 to 230 is a ((230 − 200) ÷ 200) × 100 = 15% increase. A negative result means a decrease. Use the '% increase / decrease' mode.

What is the difference between percentage change and percentage difference?

Percentage change compares a new value to an original value and has a direction (increase or decrease). Percentage difference compares two values without a 'starting point', using their average as the base. This calculator focuses on percentage change, which is what most everyday questions need.

How do I add or subtract a percentage from a price?

To add a percent (like tax), multiply the value by the percent and add it. To subtract a percent (like a discount), subtract it instead. £50 with 20% added is £60; with 20% off it's £40. The 'Add / subtract %' mode shows both at once.

Is this percentage calculator free and private?

Yes. Every calculation runs in your browser with JavaScript — nothing is uploaded or stored — and the tool is completely free with no sign-up, no limits and no ads getting in the way of the maths.