Percentage Calculator
A percentage is a number out of 100. To find a percent of a number, divide the percent by 100 and multiply: 20% of 150 = 0.2 × 150 = 30 (try it). Below are seven common percentage questions, each ready to fill in.
Pick your question and fill in the blanks
Each line answers itself as you type. Amounts like $20.50 or 1,250 work too.
- What is of ?
- is what % of ?
- is of what?
- Percent change from% change from to ?
- by
- What is of ?
- A change of then is overall
As a share
How to Use This Calculator
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Find your question
Each line is a question written out in words, such as "What is _% of _?" or "Percent change from _ to _". Pick the one that matches yours.
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Fill in the blanks
Type your numbers into that line. The answer appears at the end of the line as you type. You can include $ signs and commas.
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Read the working
Below the questions you get the answer in large type, the steps, a bar that shows the proportion, and useful related numbers.
How to calculate a percentage of a number
Percent means "per hundred", so 20% is 20 out of every 100, or 0.2 as a decimal. To take a percentage of a number, turn the percentage into a decimal by dividing it by 100, then multiply.
Say a restaurant bill is $64.50 and you want to leave an 18% tip. 18 ÷ 100 = 0.18, and 0.18 × 64.50 = 11.61, so the tip is $11.61. The order does not matter: you can also multiply 64.50 × 18 = 1,161 and divide by 100 at the end.
Shortcuts for mental math
A few tricks cover most everyday percentages without a calculator:
- 10% of a number: move the decimal point one place to the left. 10% of 64.50 is 6.45.
- 1%: move it two places. 1% of 350 is 3.5.
- 5% is half of 10%, and 20% is double 10%. For an 18% tip, take 20% and subtract 2%.
- 25% is a quarter and 50% is a half.
- x% of y is the same as y% of x. 8% of 50 is hard, but 50% of 8 is easy: both are 4.
Percentage table
This table gives common percentages of round numbers. Find the percentage on the left and read across to the number you need. For anything else, use the first line of the calculator.
| Percent | of 20 | of 50 | of 80 | of 100 | of 200 | of 500 | of 1,000 |
|---|---|---|---|---|---|---|---|
| 1% | 0.2 | 0.5 | 0.8 | 1 | 2 | 5 | 10 |
| 5% | 1 | 2.5 | 4 | 5 | 10 | 25 | 50 |
| 10% | 2 | 5 | 8 | 10 | 20 | 50 | 100 |
| 15% | 3 | 7.5 | 12 | 15 | 30 | 75 | 150 |
| 20% | 4 | 10 | 16 | 20 | 40 | 100 | 200 |
| 25% | 5 | 12.5 | 20 | 25 | 50 | 125 | 250 |
| 30% | 6 | 15 | 24 | 30 | 60 | 150 | 300 |
| 40% | 8 | 20 | 32 | 40 | 80 | 200 | 400 |
| 50% | 10 | 25 | 40 | 50 | 100 | 250 | 500 |
| 75% | 15 | 37.5 | 60 | 75 | 150 | 375 | 750 |
Percentages, decimals and fractions
A percentage, a decimal and a fraction are three ways of writing the same amount. To turn a percentage into a decimal, divide by 100: 25% becomes 0.25. To go back, multiply by 100. For a fraction, put the percentage over 100 and simplify, so 25% is 25/100, which is 1/4.
| Percent | Decimal | Fraction |
|---|---|---|
| 1% | 0.01 | 1/100 |
| 5% | 0.05 | 1/20 |
| 10% | 0.1 | 1/10 |
| 12.5% | 0.125 | 1/8 |
| 20% | 0.2 | 1/5 |
| 25% | 0.25 | 1/4 |
| 33.33% | 0.3333… | 1/3 |
| 50% | 0.5 | 1/2 |
| 66.67% | 0.6667… | 2/3 |
| 75% | 0.75 | 3/4 |
| 100% | 1 | 1 |
| 150% | 1.5 | 3/2 |
Thirds do not come out evenly. One third is 33.333…%, so it is usually rounded to 33.33% or 33.3%. When you need an exact answer, work with the fraction 1/3 and round only at the end.
How to find what percent one number is of another
To turn a part and a whole into a percentage, divide the part by the whole and multiply by 100. If you got 42 questions right out of 50, then 42 ÷ 50 = 0.84, and 0.84 × 100 = 84%. The whole always goes on the bottom of the division. It is the number that stands for 100%.
The part can be larger than the whole. If last year you sold 80 tickets and this year you sold 120, this year's sales are 120 ÷ 80 × 100 = 150% of last year's.
Show 42 out of 50 in the calculator
How to find the whole from a percentage
Sometimes you know the part and the percentage, and you need the total. Divide the part by the percentage as a decimal. If 30 is 20% of a number, the number is 30 ÷ 0.2 = 150.
The same idea gets you back to an original price. A jacket on sale for $68 after 15% off was $68 ÷ 0.85 = $80 before the sale, because after the discount you pay 85% of the price. A bill of $54 that includes 8% sales tax was $54 ÷ 1.08 = $50 before tax. A common mistake is to take 15% of the sale price and add it back. That gives $78.20, which is wrong, because the discount was taken from the original price.
Percentage change: increase and decrease
Percentage change compares a new value with an old one. Subtract the old value from the new one, divide by the old value and multiply by 100. A positive result is an increase and a negative result is a decrease.
If a price goes from $80 to $100, the change is (100 − 80) ÷ 80 × 100 = +25%. Going back from $100 to $80 is (80 − 100) ÷ 100 × 100 = −20%. The two numbers differ because each change is measured against a different starting point. The calculator shows this "change back to start" next to every result.
To apply a change instead of measuring one, multiply by 1 plus the percentage as a decimal. A 20% increase on 100 is 100 × 1.2 = 120. A 15% decrease is 100 × 0.85 = 85.
Show a price change from $80 to $100
Percent of a percent and combined percentages
To take a percentage of another percentage, multiply the two as decimals. 20% of 50% is 0.2 × 0.5 = 0.1, or 10%. This comes up whenever a share is taken from a share: if 60% of visitors sign up and 30% of those buy something, 0.6 × 0.3 = 0.18, so 18% of all visitors buy.
Changes in a row work the same way, and they never simply add up. Each change applies to the result of the one before. A price that rises 10% and then falls 10% ends at 1.1 × 0.9 = 0.99 of where it started, so it is 1% lower. A 50% gain followed by a 50% loss leaves you with 1.5 × 0.5 = 0.75, a 25% loss overall. Two discounts of 20% and 10% take 28% off in total, since 0.8 × 0.9 = 0.72.
Show a 20% discount followed by 10% more
Percentages with money
Tips, sales tax, discounts, interest and pay raises are all percentage calculations. The method is the same as with any other number, with one extra step: round the answer to the cent at the end, not in the middle. 25% of $20.50 is $5.125, which you would pay as $5.13. You can type amounts like $1,250.00 straight into the calculator and it will do the rounding.
For shopping and business there are calculators built for specific jobs: discounts and promotions, VAT and sales tax, and markup and margin.
Percentages in Excel and Google Sheets
Spreadsheets use the same formulas. Write the percentage with a % sign or as a decimal, and format the answer cell as a percentage when the result is a percent. With a number in A1 and another in B1:
- 20% of A1:
=A1*20%or=A1*0.2 - What percent A1 is of B1:
=A1/B1, then format the cell as a percentage - Percent change from A1 to B1:
=(B1-A1)/A1, formatted as a percentage - A1 increased by 15%:
=A1*(1+15%), and decreased by 15%:=A1*(1-15%)
If a cell shows 0.2 when you expected 20%, the formula is right and only the cell format is missing. If it shows 2000%, the value was multiplied by 100 twice, usually by typing 20 instead of 20% in the formula.
Percent and percentage points
When the numbers being compared are already percentages, it is easy to say the wrong thing. If a savings rate goes from 3% to 4%, it rose by 1 percentage point, which is the plain difference between the two. Measured against the old rate, though, it rose by 33.3%, because 1 is a third of 3. When you read a figure like this, check which of the two is meant before you compare it with anything.
A related mix-up is percentage error, which compares a measured value with a true value. That has its own formula and its own percent error calculator.
Frequently Asked Questions
How do you calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For 20% of 150, that is 20 ÷ 100 = 0.2, and 0.2 × 150 = 30. You can also multiply first and divide last: 20 × 150 = 3,000, and 3,000 ÷ 100 = 30.
How do you work out a percentage on a normal calculator?
Type the number, press ×, type the percentage as a decimal and press =. For 15% of 80, enter 80 × 0.15 = 12. Many calculators also have a % key, but it behaves differently from model to model, so the decimal method is the safer habit.
What is 20% of 50%?
20% of 50% is 10%. Turn both into decimals and multiply: 0.2 × 0.5 = 0.1, which is 10%. If half of a class takes Spanish and 20% of those students also take French, then 10% of the whole class takes both.
If a price goes up 10% and then down 10%, is it back where it started?
No. It ends 1% lower. The 10% drop is taken from the higher price, so it removes more than the rise added. $100 goes up to $110, then down 10% of $110, which is $11, to $99. Overall that is 1.1 × 0.9 = 0.99, a 1% decrease.
What is the difference between percent and percentage points?
Percentage points measure the gap between two percentages, while percent measures that gap relative to where you started. An interest rate that rises from 3% to 4% has gone up by 1 percentage point, but it has gone up by 33.3% compared with the old rate.
How do I calculate a percentage of money, like 25% of $20.50?
Multiply the amount by the percentage as a decimal: 0.25 × 20.50 = 5.125. Money is usually rounded to the cent, so 25% of $20.50 is $5.13. The calculator accepts amounts with a dollar, euro or pound sign and rounds the answer to the cent for you.