Percentage Calculator

Percentage calculator — free and private

Percentages come up all day — a discount at the checkout, a tip on a bill, a tax line, a grade, a price that went up or down. The trouble is that "percent" means a few different calculations, and it's easy to reach for the wrong one. This calculator puts the common questions side by side, each with its own two boxes and an answer that updates the moment you type. Nothing is uploaded — every result is worked out in your browser.

What is X% of a number?

This is the everyday discount-and-tip question. To find a percentage of a number, multiply the number by the percentage and divide by 100. A 20% tip on a $60 meal is 60 × 20 ÷ 100 = $12. A 15%-off sale on a $80 jacket takes off 80 × 15 ÷ 100 = $12, leaving $68. Type the percent and the number and the answer appears instantly.

X is what percent of Y?

Here you already have two numbers and want to know their ratio as a percentage — a score, a share, a completion rate. Divide the first by the second and multiply by 100. If you got 42 out of 50 on a test, that's 42 ÷ 50 × 100 = 84%. If 30 of 150 tickets are sold, that's 20%.

Percentage change (increase or decrease)

When something goes from one value to another, the percentage change tells you how big the move was relative to where it started. Subtract the old value from the new one, divide by the old value, and multiply by 100. A price rising from $80 to $100 is (100 − 80) ÷ 80 × 100 = a 25% increase. Falling from $100 to $80 is a 20% decrease — note the two aren't the same, because the starting point differs. The calculator labels the result as an increase or a decrease so there's no confusion.

Add or subtract a percent

Sometimes you want the final figure after a percentage is applied — a price with tax added, or a total after a discount. Adding 15% to $200 gives 200 × 1.15 = $230; subtracting 15% gives 200 × 0.85 = $170. This block shows both at once, so you can see the "with" and "without" figures together.

Everyday uses

Shopping discounts and sale prices. Restaurant tips and splitting a bill. Sales tax and VAT. Test scores and grades. Interest and simple growth. Comparing this month to last month. A percentage calculator turns all of these into a couple of taps, and having every mode on one page means you don't have to remember which formula is which.

Privacy: your numbers never leave your device

Every mode is calculated in your browser as you type. Nothing is uploaded, nothing is stored on a server, and there's no account to create. When you close the page the numbers are gone, because they were never sent anywhere in the first place.

Frequently asked questions

How do I calculate X% of a number?

Multiply the number by the percentage and divide by 100 — for example, 20% of 150 is 150 × 20 ÷ 100 = 30.

How do I find what percent one number is of another?

Divide the first number by the second and multiply by 100 — 30 out of 150 is 30 ÷ 150 × 100 = 20%.

How do I calculate percentage change?

Subtract the old value from the new, divide by the old, and multiply by 100. From 80 to 100 is a 25% increase; a negative result means a decrease.

Is my data uploaded to a server?

No. Every calculation runs in your browser — the numbers you type never leave your device, and nothing is stored or sent anywhere.