Percentage Calculator
Percent means out of 100. X% of Y is Y × X ÷ 100, so 20% of 150 is 30. X as a percent of Y is X ÷ Y × 100. Percent change is (new − old) ÷ old × 100.
What is X% of Y?
X is what percent of Y?
Percent change from X to Y
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | Y × X ÷ 100 | 20% of 150 = 30 |
| X is what percent of Y? | X ÷ Y × 100 | 450 out of 600 = 75% |
| Percent change from X to Y | (Y − X) ÷ X × 100 | 120 to 150 = 25% increase |
Using the percentage calculator
This page does one job: it answers the three questions people ask about percentages. Find the box that matches your question and type your two numbers. The answer and the working change as you type, so there is no button to press.
You can type commas in big numbers, such as 1,000 or 1,00,000, and a % sign if you like. Decimals use a point, as in 12.5.
How to calculate percentage of marks
Your marks percentage is your score as a share of the paper's total: score ÷ total × 100. Say you scored 72, 65, 81, 58 and 90 out of 100 in five subjects. That is 366 out of 500, and 366 ÷ 500 × 100 = 73.2%.
To do it here, put 366 in the marks scored box and 500 in the total marks box under the second question. Add up your subjects first, and use the total printed on your marksheet, as not every paper is out of 100.
This page works out plain percentages only. It does not turn CGPA into a percentage, because each board and university sets its own rule for that.
Percentage increase and decrease
To raise a number by a percentage, add that percentage to 100 and multiply: 800 up by 15% is 800 × 1.15 = 920. To lower it, take the percentage away from 100: 800 down by 15% is 800 × 0.85 = 680.
To find the change between two numbers, use the third question. A class going from 40 students to 34 is a 15% decrease. A town going from 12,000 people to 13,500 is a 12.5% increase.
Percentages in everyday life
- Discount: 25% off a price of 1,200 takes off 300, so the new price is 900.
- Tax: 18% on a bill of 1,000 adds 180, so the total is 1,180.
- Attendance: 68 classes out of 80 is 85%.
- Tip: 15% of a bill of 40 is 6.
- Storage: 48 GB used out of 64 GB is 75% full.
Finding the original number
Sometimes you know the percentage and the result, and you want the number you started from. If 30 is 20% of a number, that number is 30 ÷ 20 × 100 = 150.
For a price after a discount, divide by what is left. If a price is 900 after 25% off, what is left is 75%, so the old price was 900 ÷ 0.75 = 1,200. Taking 25% off and then adding 25% back does not work: that gives 1,125.
Shortcuts for doing percentages in your head
- 10%: shift the point one place left. 10% of 340 is 34.
- 5%: take 10% and halve it. 5% of 340 is 17.
- 1%: shift the point two places left. 1% of 340 is 3.4.
- 25%: divide by 4. 50%: divide by 2.
- Swap the numbers when that is easier: 8% of 50 is the same as 50% of 8, which is 4.
Two mistakes to watch for
Percent and percentage points are not the same. A pass rate going from 40% to 46% is up 6 percentage points, but it is a 15% increase.
Up and then down by the same percentage does not bring you back. 100 up by 50% is 150, and 150 down by 50% is 75, because the second percentage is taken from the bigger number.
Questions
What is the percentage formula?
Percentage = part ÷ whole × 100. For 45 out of 60, that is 45 ÷ 60 × 100 = 75%.
How do I work out the percentage of marks?
Add up your marks, then use score ÷ total × 100. 450 out of 600 is 450 ÷ 600 × 100 = 75%.
How do I find 15% of a number?
Work out the number × 15 ÷ 100. 15% of 240 is 240 × 15 ÷ 100 = 36.
How do I work out percentage increase?
Take the old number from the new one, divide by the old number and multiply by 100. From 250 to 310, that is 60 ÷ 250 × 100 = 24%.
Why does a percent change from 0 show no answer?
The formula divides by the first number, and nothing can be divided by 0. A rise from 0 has no percentage, so say how much it rose instead.
Can the answer be more than 100%?
Yes. If the part is bigger than the whole, the answer is over 100%. 150 is 150% of 100, and a number that doubles has a 100% increase.
Does this page keep the numbers I type?
No. The calculations run in your browser, and nothing you type is saved or sent to our server.
Is the percentage calculator free?
Yes. It runs in the browser on phones and computers, with no sign-up and nothing to install.
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