Percentage Calculator
By Santaji GadepatilinUpdated October 27, 2026
calculated
Type in any field to change it. Press × on a value to calculate that field instead.
Result (part) vs Percentage (%) — other inputs held at your current values.
How to use this calculator
This one calculator answers all three common percentage questions. Fill in any two fields and the third is calculated:
| You know | You get | Example |
|---|---|---|
| Percentage and whole | Part | 15% of 240 = 36 |
| Part and whole | Percentage | 36 of 240 = 15% |
| Part and percentage | Whole | 36 is 15% of 240 |
To switch question, press × on the field you want calculated, then type the other values.
The formula
part = percentage × whole
A percentage is a fraction of 100, so 15% means 15 ÷ 100 = 0.15. Rearranging the same formula gives the other two forms:
- percentage = part ÷ whole
- whole = part ÷ percentage
Quick mental tricks
- 10% — move the decimal point one place left (10% of 240 = 24).
- 5% — half of 10% (12).
- 15% — 10% + 5% (24 + 12 = 36).
- x% of y = y% of x — 8% of 50 is the same as 50% of 8, which is 4.
Common mistakes
- Percentage points vs percent. A rate rising from 4% to 5% is a rise of 1 percentage point but 25 percent. Use the percentage change calculator for the second kind.
- Adding percentages in sequence. A 20% rise followed by a 20% fall does not return to the start: 100 → 120 → 96.
Frequently asked questions
How do I calculate a percentage of a number?
Convert the percentage to a decimal and multiply. 15% of 240 is 0.15 × 240 = 36.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 36 out of 240 is 36 ÷ 240 × 100 = 15%. Here, press × on Percentage and type the part instead.
How do I find the whole if I know the part and the percentage?
Divide the part by the percentage as a decimal. If 36 is 15%, the whole is 36 ÷ 0.15 = 240.