Percentage Calculator
Percent questions come in a few shapes. This page has a box for each one, so you can fill in the one that matches your question and read the answer straight away.
Use it for discounts, tips, tax, grades, pay changes, price increases and anything else where you need to turn a percent into a number, or a number into a percent.
How it works
A percent is a number out of 100. So “15%” means 15 out of every 100, or 0.15. To find 15% of 80, multiply 80 by 15 and divide by 100. That gives 12.
To find what percent one number is of another, divide the part by the whole and multiply by 100. So 18 out of 60 is 18 ÷ 60 × 100 = 30%.
Percent change compares a new number with an old one. Subtract the old number from the new, divide by the old number, and multiply by 100. A positive answer is an increase and a negative answer is a decrease. Going from 50 to 65 is up 30%. Going from 200 to 150 is down 25%.
To raise a number by a percent, add that percent of it. To lower it, subtract that percent of it. To find the original number when you know a part and its percent, divide the part by the percent and multiply by 100.
A common trap: a 50% rise followed by a 50% drop does not get you back to the start. Take 100, raise it 50% to get 150, then drop 50% to get 75. The second percent is taken from a bigger number.
X% of Y = Y × X ÷ 100
A is what % of B = A ÷ B × 100
change % = (new − old) ÷ old × 100
raise Y by X% = Y + Y × X ÷ 100
A is X% of what = A ÷ X × 100Worked example: Five quick questions
15% of 80 is 12. 18 is 30% of 60. From 50 to 65 is a 30% increase.
Raise 200 by 15% to get 230, or lower it by 15% to get 170. And 30 is 12% of 250.
Frequently asked questions
How do I work out a discount?
Use “What is X% of Y” to find the amount off, then subtract it from the price. Or use “Decrease Y by X%” to get the sale price straight away.
What is the difference between percent and percentage points?
If a rate goes from 4% to 6%, it rose by 2 percentage points, which is a 50% increase in the rate itself. People often mix these up in news stories.
Why is percent change different going up and going down?
Because each change is measured against its own starting number. A rise from 80 to 100 is 25%, but a fall from 100 to 80 is 20%.
Can a percent be over 100?
Yes. 150% of a number is one and a half times it. A change of 200% means the new number is three times the old one.
How do I find the original price before a discount?
Use “A is X% of what”. If you paid $60 after a 25% discount, you paid 75% of the original price. So 60 is 75% of what, which is 80.
Related tools
- Tip CalculatorWork out the tip, the total and each person’s share in one step. Pick a tip percent, set the number of people, and round up if you like.
- Margin CalculatorWork out profit margin and markup from cost and price, or find the price you need for a target margin. Clears up the margin versus markup mix-up.
- Pay Raise CalculatorSee what a raise is worth per hour, week, month and year. Enter a percent raise or a new pay amount and compare before and after.
Content last reviewed 2026-10-13.