Percentage Calculator
Work out X% of Y, what percent X is of Y, or the % change between two values.
Solve the three most common percentage problems
Percentage Calculator handles three kinds of question: finding a percentage of a number, finding what percentage one number is of another, and working out the percentage change from one value to another.
Each kind has its own tab with the question written out around the boxes, so you fill in the blanks instead of trying to remember which number divides which. The sums are done in your browser.
How to work out a percentage
- Pick a tab: X% of Y, X is what % of Y, or % change.
- Fill in the two boxes. The words around them read as the question — for example, “What is 20 % of 150”.
- Click Calculate.
- Switch tabs for a different type of question. Each tab keeps its own numbers, so you can go back and forth.
Reading the result in each mode
- X% of Y gives a plain number: 20% of 150 is 30.
- X is what % of Y gives a percentage: 30 is 20% of 150.
- % change gives the rise or fall relative to the starting value, labelled as an increase or decrease, with a + sign for a rise. Going from 100 to 125 is +25%; from 125 back to 100 is −20%.
- Rounding: every result is rounded to two decimal places, so 1 out of 3 shows as 33.33%.
Everyday percentage questions
- Discounts: find 15% of a price with X% of Y, then take it off the original.
- Fees and tips: work out a service charge, a commission or a tip on a bill.
- Marks and scores: turn 42 out of 60 into a percentage with X is what % of Y — it’s 70%.
- Prices and pay: see how much a bill, rent or salary has changed with % change.
- Foreign prices: convert an amount with the Currency Converter, then add tax or a margin here.
Percentage change, explained
Why a rise and a fall don’t cancel out
Percentage change is always measured against the starting value. A price that goes from 100 to 125 has risen 25%, but cutting 125 by 25% gives 93.75, not 100, because the 25% is now taken from a bigger number. To get back to 100 it has to fall 20%.
Percentage change vs percentage points
When the thing changing is itself a percentage — an interest rate moving from 4% to 5%, say — the difference is 1 percentage point, but the percentage change is 25%. Enter 4 and 5 in the % change tab for the second figure; simply subtract them for the first.
Percentage Calculator: common questions
How do I calculate a discount?
Use X% of Y with the discount and the original price: 25% of 80 is 20, so the sale price is 60. You can also get the sale price in one step by finding 75% of 80.
How do I find what percentage one number is of another?
Use the X is what % of Y tab, with the part in the first box and the whole in the second. For example, 45 is 25% of 180.
Does % change work with negative numbers?
Yes. The change is measured against the size of the starting value, so going from −50 to −25 shows as a 50% increase.
Why isn’t a result showing?
A percentage change can’t be calculated from a starting value of 0, and “X is what % of Y” needs a second number other than 0, so in those cases the calculator explains why instead of showing a number. Both boxes also need a value — an empty box isn’t treated as 0.
Can it add a percentage to a number directly?
Not in one step. Find the percentage with X% of Y, then add it — or find 100% plus the increase, such as 120% of the amount for a 20% markup. More number tools are in Calculators.