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Percentage calculator

Four percentage operations, computed instantly in your browser, nothing leaves your device.

How Percentage calculator works

The percentage calculator covers the four everyday percentage questions in one place: what is X% of Y, X is what percent of Y, the percentage change from one value to another, and increasing or decreasing a value by a percentage. Pick the calculation, type two numbers, and the answer appears instantly.

Decimals and negative numbers are accepted throughout, so the change mode handles a drop from a negative starting value correctly, and the increase/decrease mode doubles as a quick discount, markup or tax helper.

Frequently asked questions

Does this calculator send my numbers to a server?

No. All the maths runs locally in your browser; nothing you type is uploaded or stored. You can disconnect after the page loads and it keeps working.

How is percentage change calculated?

Percentage change from X to Y is (Y − X) divided by the absolute value of X, times 100. A rise is positive and a fall is negative, even when X is negative.

What does "increase/decrease by %" do?

It applies the percentage to a base value: increase multiplies by (1 + p/100), decrease multiplies by (1 − p/100). Useful for discounts, markups, tips and taxes.

Can I use decimals and negative numbers?

Yes. Enter any decimal (e.g. 12.5) or negative value; the result is shown to a sensible precision.

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