Percentage Calculator
Instantly find what percent of a number is, calculate percentage increase or decrease, or find what percentage one number is of another. Just enter your values and click Calculate.
Notes
What is a Percentage?
A percentage is a number expressed as a fraction of 100. The word comes from the Latin 'per centum' meaning 'by the hundred'. Percentages are used in everyday life — discounts, tax rates, test scores, statistics, and more.
The Core Formula
To find a percentage of a number, multiply the number by the percentage and divide by 100:
Example: What is 25% of 200?
Common Percentage Calculations
| What you want to find | Formula | Example |
|---|---|---|
| X% of Y | (Y × X) / 100 | 25% of 200 = 50 |
| What % is A of B | (A / B) × 100 | 50 is 25% of 200 |
| Percentage increase | ((New − Old) / Old) × 100 | 80 → 100 is 25% increase |
| Percentage decrease | ((Old − New) / Old) × 100 | 100 → 80 is 20% decrease |
Percentage Increase and Decrease
To calculate the percentage change between two values:
Finding What Percentage One Number Is of Another
To find what percentage a part is of the whole, divide the part by the whole and multiply by 100:
Step-by-step example — 30 is what percent of 150?
- Part = 30, Whole = 150
- Divide: 30 ÷ 150 = 0.2
- Multiply by 100: 0.2 × 100 = 20
- Answer: 30 is 20% of 150
Quick Reference
- 50% of a number = divide by 2
- 25% of a number = divide by 4
- 10% of a number = move decimal one place left
- 1% of a number = move decimal two places left
- 100% of a number = the number itself
- How to calculate percentages — full explanation — Step-by-step worked examples and common use cases
- Percentage formula derivation in depth — Formula breakdown with variable definitions
Frequently Asked Questions
How do I calculate 20% of a number?
Multiply the number by 0.20, or equivalently multiply by 20 and divide by 100. For example, 20% of 350 = 350 × 0.20 = 70.
What is the percentage formula?
Percentage = (Part ÷ Whole) × 100. To find a part from a percentage: Part = (Percentage ÷ 100) × Whole.
How do I calculate a percentage increase?
Percentage Increase = ((New Value − Old Value) / Old Value) × 100. For example, going from 80 to 100: ((100 − 80) / 80) × 100 = 25% increase.
What is 100% of a number?
100% of any number equals the number itself. For example, 100% of 75 = 75.
How do I find what percentage A is of B?
Divide A by B and multiply by 100. For example, 15 is what percent of 60? Answer: (15 / 60) × 100 = 25%.
Can percentages be greater than 100?
Yes. A percentage greater than 100 means the part exceeds the whole. For example, if profits grew from $50 to $130, that is a 160% increase.