The Percentage Calculator handles the four percentage questions that come up most often — and shows the answer the moment you type, so there is nothing to wait for.

What is X% of a number?

Use this for tips, sales tax, interest, exam marks, or any share of a total. For example, 15% of 80 is 12. The maths is simply the number multiplied by the percentage, divided by 100.

One number is what percent of another?

Turn a part and a whole into a percentage. If you scored 45 out of 60, that is 75%. Divide the part by the whole and multiply by 100.

Percentage increase or decrease

Measure how much a value has changed. From 200 to 250 is a 25% increase; from 250 to 200 is a 20% decrease. The calculator shows the direction and the actual difference too.

Increase or decrease a number by a percent

Apply a discount or a mark-up in one step. A 1,200 price reduced by 20% is 960; increased by 20% it is 1,440. Both results are shown side by side.

Inputs are forgiving — commas, spaces, and a trailing “%” are ignored, so you can paste figures straight in. Nothing is uploaded; the calculation runs in your browser, and any saved entries stay on your own device.