Percentage Calculator
Percentages appear in discounts, tax, marks, interest and statistics. Choose the type of question you have, enter the two numbers and get the answer with the working shown.
Results
Result
30
15% of 200 is 30.
Show the calculation steps
- Convert the percentage to a decimal: 15% ÷ 100 = 0.15.
- Multiply by the number: 0.15 × 200 = 30.
What is a percentage?
A percentage is a fraction of 100. Saying 15% means 15 out of every 100, or 0.15. To find a percentage of a number, you multiply the number by the percentage divided by 100.
The five calculations
This calculator covers the situations people run into most often:
- X% of a number: for example, the tip on a bill or the tax on a price.
- What percent one number is of another: for example, a test score out of a maximum.
- Percentage change: how much a value has risen or fallen compared with where it started.
- Increase by a percentage: for example, adding tax or a price rise.
- Decrease by a percentage: for example, applying a discount.
Percentage change is not symmetric
A price that rises by 50% and then falls by 50% does not return to where it started: 100 becomes 150, and a 50% fall takes it to 75. Percentage change is always measured against the starting value, so the same absolute change gives a different percentage in each direction.
Formula
X% of Y = X ÷ 100 × Y
Percent = Part ÷ Total × 100
Percentage change = (New − Old) ÷ |Old| × 100
Increase: New = Number × (1 + Percent ÷ 100) · Decrease: New = Number × (1 − Percent ÷ 100)
Where:
- X, Percent
- = The percentage
- Y, Number, Total
- = The number the percentage applies to
- Old, New
- = The starting and ending values
Example calculation
What is 15% of 200?
Inputs
- What do you want to find?
- X% of a number
- Percentage
- 15 %
- Of the number
- 200
Result
- Result
- 30
Step-by-step
- Convert the percentage to a decimal: 15% ÷ 100 = 0.15.
- Multiply by the number: 0.15 × 200 = 30.
Percentage change from 80 to 100
Inputs
- What do you want to find?
- Percentage change between two numbers
- From (old value)
- 80
- To (new value)
- 100
Result
- Percentage change
- 25%
- Difference
- 20
Step-by-step
- Find the difference: 100 − 80 = 20.
- Divide by the starting value: 20 ÷ 80 = 0.25.
- Multiply by 100: 25%.
Important notes
- Percentage change from a negative starting value is measured against its absolute value, so going from −50 to 50 is a +200% change.
- A percentage change from zero is undefined and is reported as an error.
Disclaimer: This calculator provides estimates for informational purposes only. Check important results independently before relying on them.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 15 ÷ 100 × 200 = 30.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100 the change is (100 − 80) ÷ 80 × 100 = 25%. A negative result is a decrease.
How do I work out what percent one number is of another?
Divide the part by the total and multiply by 100. Scoring 45 out of 60 gives 45 ÷ 60 × 100 = 75%.
Why can't I calculate a percentage of zero?
Expressing a value as a percentage of zero, or measuring change from zero, would need division by zero, which has no defined result. The calculator asks for a non-zero number instead of showing a misleading answer.
What is the difference between percentage and percentage points?
Going from 4% to 6% is a rise of 2 percentage points, but a 50% increase in the rate itself. Use the percentage change mode for the second meaning.
Related calculators
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- Average CalculatorFind the mean, median, mode, sum, count, smallest, largest and range of any list of numbers, with the calculation steps shown.
- Profit Margin CalculatorCalculate profit, profit margin and markup from cost and selling price, or find the selling price you need to reach a target margin.
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