Free Percentage Calculator
Instantly calculate percentages, increases, and differences — with the formula shown every time.
Popular Examples
- 25% of 200 = 50
- 15% tip on $80 = $12
- 30% off $150 = $105
- Increase from 100 to 120 = 20% increase
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How to Calculate Percentages
A percentage is a way of expressing a number as a fraction of 100. The word itself comes from the Latin per centum, meaning "by the hundred." Whenever you see a percentage, you can picture it as a share out of 100 equal parts — 50% is 50 of those 100 parts, or exactly half.
The core formula behind almost every percentage calculation is the same:
part = (percent ÷ 100) × whole
From that one relationship, you can rearrange to solve for whichever value you're missing. Want to know what percentage one number is of another? Divide the part by the whole and multiply by 100. Need to find the original whole from a known part and percentage? Divide the part by the percentage (as a decimal). The four tools above cover the most common versions of this problem — a straight percentage of a number, the percent change between two numbers, working backward to a reverse percentage, and the percent difference between two values that don't have a fixed "before."
Quick Reference: Common Percentages as Decimals
| Percent | Decimal | Fraction |
|---|---|---|
| 1% | 0.01 | 1/100 |
| 5% | 0.05 | 1/20 |
| 10% | 0.10 | 1/10 |
| 25% | 0.25 | 1/4 |
| 50% | 0.50 | 1/2 |
| 75% | 0.75 | 3/4 |
Need to convert an unusual percentage? Try the Percent to Decimal Converter.
Frequently Asked Questions
How do you calculate a percentage of a number?
Divide the percentage by 100 to get a decimal, then multiply by the number. For example, 25% of 200 is (25 ÷ 100) × 200 = 50.
How do you calculate percentage change between two numbers?
Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result is an increase; a negative result is a decrease.
What is a reverse percentage calculation?
A reverse percentage finds the original whole number when you know a part and what percentage that part represents. Divide the known amount by the percentage expressed as a decimal.
What's the difference between percentage change and percentage difference?
Percentage change compares a new value to an original value and has a direction (increase or decrease). Percentage difference compares two values with no fixed "original," using their average as the base, so it's always positive.