🔢 Percentage of a Number Calculator MAIN TOOL
Related Percentage Tools
How Do You Work It Out?
To find a percentage of a number, divide the percentage by 100 and multiply by the number: 20% of 150 = 0.20 × 150 = 30. To find what percent one number is of another, divide and multiply by 100: 30 is 20% of 150. Enter two values above and the calculator shows the answer and the working.
Quick Reference
| of 40 | of 80 | of 150 | of 250 | of 1,200 | |
|---|---|---|---|---|---|
| 5% | 2 | 4 | 7.5 | 12.5 | 60 |
| 10% | 4 | 8 | 15 | 25 | 120 |
| 15% | 6 | 12 | 22.5 | 37.5 | 180 |
| 20% | 8 | 16 | 30 | 50 | 240 |
| 25% | 10 | 20 | 37.5 | 62.5 | 300 |
| 30% | 12 | 24 | 45 | 75 | 360 |
| 50% | 20 | 40 | 75 | 125 | 600 |
The Formula
Result = (Percentage ÷ 100) × Number
Worked Example
What is 15% of 200? Result = (15 ÷ 100) × 200 = 30.
Common Everyday Uses
This calculation shows up constantly in daily life: figuring out a tax amount on a purchase, calculating a commission on a sale, finding a portion of a recipe, working out interest on a balance, or checking what a grade percentage translates to in raw points. Use the quick-select buttons above for common percentages like 10%, 25%, or 50%.
A Useful Shortcut for Mental Math
For quick mental estimates: 10% of any number just moves the decimal point one place left (10% of 250 = 25). From there, 5% is half of that, 20% is double, and 15% is 10% + 5%. This mental shortcut is handy when you don't have a calculator on hand, though for anything beyond a rough estimate, use the exact calculator above.
Percentage of a Percentage
This calculator also handles a "percentage of a percentage," which just means treating the second percentage as the number. For example, 20% of 50% is 10%, since (20 ÷ 100) × 50 = 10. This comes up when combining discounts, commission splits, or any scenario where one rate is applied on top of another.
Finding the Reverse: What Percentage Is One Number of Another
If instead you know two numbers and want the percentage they represent, use (Part ÷ Whole) × 100. For example, if you scored 42 out of 50 on a test, that's (42 ÷ 50) × 100 = 84%. This is the reverse of what this calculator does above, and it's the same formula our percentage hub page explains in more detail.
Need the change between two numbers instead? Use the percentage change calculator, or find a sale price with the discount calculator. All tools are in the percentage calculator hub.
How to Use the Percentage of a Number Calculator
- To find a percentage of a number, enter the percentage and the number (for example 15% of 240).
- To find what percent one number is of another, enter the part (X) and the whole (Y).
- Read the answer, shown with the calculation behind it.
Who Uses the Percentage of a Number Calculator?
- Tips and taxes: find 15% of a bill or the VAT on a price.
- Grades: turn 42 out of 50 into a percentage.
- Budgets: see what share of income goes on rent.
How the Percentage of a Number Calculator Saves You Time
Converting a percentage to a decimal and multiplying is quick on paper but easy to slip on. The calculator answers both kinds of question in one step.
Frequently Asked Questions
What is 15% of 200?
How do I calculate a percentage of a number?
Is there a quick mental math trick for percentages?
What's the difference between "X% of Y" and "X is what % of Y"?
How do I calculate a percentage of a percentage?
How do I find what percentage one number is of another?
Last updated: September 2026