Percentage Calculator
Work out any percentage in seconds: percent of a number, what percent one number is of another, percentage change, raises and discounts.
How to use the percentage calculator
- Choose the kind of calculation from the tabs at the top of the calculator.
- Type your numbers. Decimals work with either a dot or a comma.
- The answer appears instantly, together with the formula and a few related figures.
- Press Copy result to paste the answer anywhere.
Percentages, explained simply
A percentage is a number expressed as a part of 100. The word comes from the Latin per centum, "by the hundred". So 25% means 25 out of every 100, which is the same as the fraction 1/4 or the decimal 0.25. Percentages make it easy to compare things of different sizes: a 30-point score out of 40 and a 75-point score out of 100 are both 75%.
The basic formula
Every percentage problem uses the same three pieces: the part, the whole and the percentage. If you know any two, you can find the third.
part = whole × percentage ÷ 100
percentage = part ÷ whole × 100
whole = part ÷ percentage × 100
That is exactly what the first, second and last tabs of this calculator do. Percent of finds the part, What percent finds the percentage and Find the whole finds the original total.
Percentage change
To see how much something grew or shrank, compare the difference with the starting value:
change % = (new − old) ÷ old × 100
If a monthly bill goes from 80 to 100, the change is (100 − 80) ÷ 80 × 100 = 25%, an increase. If it drops from 100 to 80, the change is −20%. The two numbers are different because each one is measured against a different starting point. Try it on the Percent change tab.
Adding or removing a percentage
To raise a number by a percentage, multiply it by (1 + rate). A 15% raise on 2,000 gives 2,000 × 1.15 = 2,300. To lower it, multiply by (1 − rate): a 15% discount on 200 leaves 200 × 0.85 = 170.
A common mistake is to undo a percentage by subtracting the same rate. If a price of 100 includes 20% tax and you take 20% off 120, you get 96, not 100. The right way is to divide: 120 ÷ 1.20 = 100. On the Find the whole tab, enter 120 as the part and 120 as the percentage to get the price before tax. For a full net, tax and total breakdown, use the VAT calculator.
Everyday uses
- Shopping: work out sale prices, compare discounts and check the final price after tax.
- Money: calculate tips, salary raises, interest and how much an investment went up or down.
- School and work: turn test scores into percentages, track progress toward a goal and report growth.
- Health: follow changes in weight, steps or other measurements over time.
All calculations run in your browser. Nothing you type is sent to a server, and the page works even with a slow connection once it has loaded.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 is 150 × 20 ÷ 100 = 30. A quick shortcut for 10% is to move the decimal point one place to the left.
How do I calculate a percentage increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%. A negative result means the value went down.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value with a starting value, so the direction matters. Percentage difference compares two values with their average, so it is the same whichever order you enter them. Both are shown on the Percent change tab.
How do I find the price before tax or before a discount?
Divide by the percentage that remains. A price of 120 that includes 20% tax was 120 ÷ 1.20 = 100 before tax. A price of 85 after a 15% discount was 85 ÷ 0.85 = 100. Use the Find the whole tab and enter 120% or 85% as the percentage.
Are my numbers saved or sent anywhere?
No. The calculator runs entirely in your browser and nothing is uploaded. Only your last selected tab is remembered on your own device.