Percentage Calculator

Percentage Calculator answers four everyday percentage questions from two numbers: a percent of a number, what percent one is of another, a percentage change, and a percent added or subtracted. It suits shoppers checking a discount, students doing homework, and anyone comparing two figures in a report. The answer updates as you type, and it shows the working so you can check it by hand.

How to use

1. Choose a question from the list: X% of Y, X is what % of Y, Percentage change from X to Y, or Add or subtract X% to Y.
2. Type your two numbers into the boxes. Their labels change with the question, so you always know which number goes where.
3. For the add or subtract question, also choose whether the percent is added or subtracted.
4. Read the Result cell, the sentence under it and the line that begins “Worked as”. Some questions add a second cell, such as the difference between the two numbers.
5. If a box is empty or cannot be read, a message under it says what to fix.

Examples

The page opens on this one: X% of Y with 15 and 80 gives 12, because 15 × 80 ÷ 100 is 12.

Switch to X is what % of Y with 20 and 80 and the result is 25%. For Percentage change from X to Y, going from 50 to 75 is an increase of 50%, and going from 80 to 60 is a decrease of 25%. For Add or subtract X% to Y, adding 20% to 50 gives 60, and subtracting 20% from 50 gives 40.

Limits

Each number may be up to 1,000,000,000,000,000 in size, positive or negative, and answers are shown with at most 6 decimal places. Commas are accepted only as thousands separators, so 1,234.5 works but 1,5 does not. Scientific notation such as 1e5 is refused. A total of 0 cannot be divided into, and a percentage change cannot start from 0. For a negative starting value the change is measured against its size, ignoring the minus sign.

FAQ

How do I work out the percentage change between two numbers?

Choose the percentage change question, put the old value in the From box and the new value in the To box. The result is the difference divided by the starting value, times 100. A positive result is an increase and a negative one is a decrease.

Why does it say a change from 0 has no percentage?

A percentage change divides by the starting value, and dividing by 0 has no answer. The same reason explains the message about a total of 0 in the question that asks what percent one number is of another.

Can I use a percent above 100 or a negative number?

Yes. A percent above 100 gives a result larger than the number itself, and subtracting more than 100% gives a negative answer. Negative numbers are read as typed, so the result follows the usual signs.

Are my numbers sent anywhere?

No. The sums run inside this page on your device, and nothing you type is uploaded or stored.