X% of a value
result = V × X ÷ 100
Multiply the value by the fraction X/100.
Calculate X% of a number
Work out X% of a number or an amount instantly: a share of a total, sales tax, a tip, a deposit, a commission or a discount. Formula value × X ÷ 100, mental math shortcuts (10%, 1%, 25%) and worked examples.
Result
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How does this tool work?
This page calculates X% of a number: what 20% of 150 is, how much an 8% sales tax adds, the size of a 30% deposit or a 20% tip. It is the most common percentage calculation, useful for a bill, a commission, a share of a budget, a test score or a recipe quantity.
Taking X% of a value means multiplying it by X and dividing by 100: result = value × X ÷ 100. For 20% of 150: 150 × 20 ÷ 100 = 30. "Per cent" literally means "per hundred": 20% is the fraction 20/100, or 0.2.
The calculation works both ways: X% of Y equals Y% of X. So 8% of 50 is easier to compute as 50% of 8, which is 4. This property is a big help for mental math.
To calculate in your head, start from simple percentages: 10% means dividing by 10, 1% dividing by 100, 50% dividing by 2 and 25% dividing by 4. 15% of 80 = 10% (8) + 5% (4) = 12.
The result is in the same unit as the value: a percentage of dollars gives dollars, a percentage of grams gives grams. Percentages above 100 and decimal percentages are accepted: 150% of 40 is 60, 5.5% of 200 is 11.
How to use this tool
Enter the percentage
For example 20 for 20%; decimals are accepted (5.5 or 2.75).
Enter the value
The amount, quantity or total you want to take a share of.
Read the result
The matching share appears immediately, rounded to two decimal places.
The formula for a percentage of a value
A percentage is a fraction with a denominator of 100.
Decimal form
X% = X ÷ 100
20% = 0.2; 5.5% = 0.055; 150% = 1.5.
Symmetry
X% of Y = Y% of X
Handy for mental math.
- V
- value or reference total
- X
- percentage applied
Example: 12% of 250 = 250 × 0.12 = 30.
Use cases
Bills and purchases
Calculate sales tax, a service charge, a tip, a deposit or a shipping fee expressed as a percentage.
Commissions and pay
Work out a sales commission, a performance bonus or a contribution expressed as a percentage of an amount.
Budgeting and savings
Split an income by percentages, for example with the 50/30/20 rule, or set a monthly savings amount.
Cooking, fitness and science
Measure an ingredient, set a training intensity or find the mass of a component from its proportion.
Examples
Basic calculation
150 × 20 ÷ 100 = 30.
Input
20% of 150Result
30Restaurant tip
10% is $6.40, doubled to get 20%: $12.80.
Input
20% of $64Result
$12.80Deposit
Amount due when signing a $2,450 quote.
Input
30% of $2,450Result
$735Sales tax
180 × 8 ÷ 100 = $14.40 of tax on a $180 purchase.
Input
8% of $180Result
$14.40Swap trick
Easier as 25% of 8 = 8 ÷ 4 = 2.
Input
8% of 25Result
2Tips and best practices
- 10% of a number is that number divided by 10: use it as a starting point for 5%, 15% or 20%.
- X% of Y = Y% of X: pick the order that makes the calculation easiest.
- To add a percentage to a value or take one off, use the percentage increase or decrease pages instead.
- To find what percentage a value is of a total, you need the reverse operation: use the dedicated page.
Sources and references
- Weisstein E.W., Percent (opens in a new tab), Wolfram MathWorldPage in English
- Programme de mathématiques pour le cycle 4 (annexe 2) (opens in a new tab), Ministère de l’Éducation nationalePage in French
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage, then divide by 100. For example, 35% of 240 = 240 × 35 ÷ 100 = 84.
How do I work out 10%, 20% or 25% in my head?
10%: divide by 10. 20%: divide by 10, then multiply by 2. 25%: divide by 4. For 20% of 45: 4.5 × 2 = 9.
How do I calculate 5% of an amount?
Take 10% of the amount, then halve it. 5% of $360 = 36 ÷ 2 = $18.
Can a percentage be more than 100%?
Yes. 150% of a value is one and a half times that value: 150% of 40 = 60. This happens with growth or when a target is exceeded.
How is this different from "what percentage is X of Y"?
Here you know the percentage and want the share: 20% of 150 = 30. In the other case you know the share and the total and want the percentage: 30 out of 150 = 20%.
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