Percentage calculator
Calculate percentages online, free and instantly.
Whether you’re splitting a restaurant bill, checking a discount, working out a grade, or tracking business growth, percentages come up all the time. Enter your numbers and use the calculator above for a quick result. Below, find simple steps, formulas, and examples to help you check the math.
- Free to use
- No sign-up required
- Works on phones and computers
What it does
What is this percentage calculator?
This free online percentage calculator has dedicated keys for finding a percentage of a number, adding a percentage to a number, and subtracting a percentage from a number. It also supports addition, subtraction, multiplication, and division. For other questions, such as finding what percent one value is of another or comparing percentage change, use the reference formulas and examples below.
Find a percentage of a number
For example, find 20% of 150. Use the % of key.
Add a percentage
For example, add 10% to 200. Use the +% key.
Subtract a percentage
For example, take 15% off 200. Use the -% key.
How it works
How to calculate a percentage using a calculator.
Enter the starting number first, select a percentage operation, enter the rate, and calculate.
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Enter the starting number
Use the keypad to enter the total or original value.
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Choose the operation
Select % of, +%, -%, addition, subtraction, multiplication, or division.
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Enter the percentage rate
Type the percentage you want to calculate, such as 20.
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Get the result
Select equals. Your calculation is added to the history below the keypad.
Find 20% of 150
Enter 150 → % of → 20 → =
Result: 30
Add 10% to 200
Enter 200 → +% → 10 → =
Result: 220
Take 15% off 200
Enter 200 → -% → 15 → =
Result: 170
Manual methods
How to calculate a percentage on a basic calculator.
The same formulas work on a phone calculator, a basic calculator, or a scientific calculator.
Find X% of a number
For 20% of 150, calculate 20 ÷ 100 × 150 = 30. If your calculator’s % key works for this operation, you can also enter 20, press %, then multiply by 150.
Find what percent one number is of another
For “30 is what percent of 150?”, calculate 30 ÷ 150 × 100 = 20%.
Calculate an increase or decrease
Subtract the starting value from the new value, divide by the starting value, and multiply by 100. Use the sign or label to distinguish an increase from a decrease.
A % key can behave differently across calculator models. When unsure, divide the rate by 100 first; this method works consistently. For critical calculations, check the formula and result.
Formula reference
The percentage calculator formula.
A percentage expresses a value as parts per hundred. These formulas cover common percentage questions.
| What you want to find | Formula | Example |
|---|---|---|
| What is X% of Y? | (X ÷ 100) × Y | 20% of 150 = 30 |
| X is what percent of Y? | (X ÷ Y) × 100 | 30 of 150 = 20% |
| Percentage increase | ((New − Old) ÷ Old) × 100 | 80 to 100 = 25% increase |
| Percentage decrease | ((Old − New) ÷ Old) × 100 | 100 to 80 = 20% decrease |
| Percentage difference | (|A − B| ÷ ((A + B) ÷ 2)) × 100 | 40 and 60 = 40% difference |
The percentage keys handle “X% of Y,” adding a percentage, and subtracting a percentage. The keypad also includes standard addition, subtraction, multiplication, and division. Use the formulas above as a guide for other types of percentage questions.
The quick answer
How do you calculate percentages?
To find what percent one number is of another, divide the part by the whole and multiply by 100. That rule works for grades, discounts, taxes, tips, and many everyday percentage questions.
Grade
45 out of 60: (45 ÷ 60) × 100 = 75%
Discount
25% off $120: $120 × 0.25 = $30 off; sale price = $90
Tax
8% of $250: (8 ÷ 100) × $250 = $20 tax; total = $270
Tip
18% of an $85 bill: $85 × 0.18 = $15.30
Growth
Revenue from 400 to 500: ((500 − 400) ÷ 400) × 100 = 25% increase
Learn the basics
Types of percentage calculations.
1. Finding a percentage of a number
Find a part of a total. Example: 15% of 200 = (15 ÷ 100) × 200 = 30. Use this for discounts, taxes, tips, commissions, and interest.
2. Finding what percent one number is of another
Divide the part by the whole and multiply by 100. Example: 42 correct answers out of 50 = (42 ÷ 50) × 100 = 84%.
3. Percentage increase
Compare a new value with the starting value. Example: a price from $80 to $100 changes by ((100 − 80) ÷ 80) × 100 = 25% increase.
4. Percentage decrease
Compare a lower value with the starting value. Example: a price from $100 to $80 changes by ((100 − 80) ÷ 100) × 100 = 20% decrease.
Everyday math
When should you use an online percentage calculator?
Use it when you need a quick percentage result without doing the arithmetic by hand.
- Shopping and discountsCheck a sale price, compare percentage discounts, or calculate cashback.
- Restaurant tipsWork out a tip amount or check the percentage added to a bill.
- Tax and VATCalculate a percentage tax amount and add it to a purchase total.
- School and educationConvert marks into a score percentage or check course completion.
- Business and financeReview growth, margins, expenses, commissions, or interest figures.
- Loans and interestWork through percentage rates and compare figures when reviewing loan or interest information.
- Health and fitnessCompare changes in weight or other measurements against a starting value.
- Everyday budgetingWork out how much of a monthly budget goes to a category.
Questions
Percentage calculator FAQs.
How do you calculate percentages?
To find what percent a part is of a whole, divide the part by the whole and multiply by 100. For example, 25 out of 200 is (25 ÷ 200) × 100 = 12.5%.
How do I calculate a percentage using a calculator?
For “X% of Y,” enter Y, select % of, enter X, then select equals. On a basic calculator without a percentage operation, calculate (X ÷ 100) × Y.
What is the percentage calculator formula?
The general formula is Percentage = (Part ÷ Whole) × 100. Percentage of a number, increase, decrease, and difference use related formulas shown in the reference table above.
What is 20% of 150?
20% of 150 is (20 ÷ 100) × 150 = 30. In the calculator, enter 150, select % of, enter 20, and select equals.
How do I calculate a percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100. For example, going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.
How do I calculate a percentage decrease?
Subtract the new value from the old value, divide by the old value, and multiply by 100. For example, going from 100 to 80 is ((100 − 80) ÷ 100) × 100 = 20% decrease.
Is this percentage calculator accurate?
The calculator applies the percentage operations shown above. As with other calculators, displayed decimal results can depend on the precision of the browser’s number arithmetic.
Can I use this percentage calculator on my phone?
Yes. The calculator works in a mobile web browser as well as on tablets and desktop computers. No app download is required.
Where is my calculation history saved?
Calculation history is saved in this browser on your device. Use Clear History to remove the saved history for this calculator.