How to Calculate a Percentage
Learn the basic percentage formula with a clear example and quick ways to check the result.
Find 20% of 250
Formula: (20 ÷ 100) × 250 = 50.
The basic method
The percent sign means “per hundred.” Dividing by 100 turns the percentage into a multiplier. Multiply that decimal by the original number to find the percentage amount.
- 10% becomes 0.10.
- 25% becomes 0.25.
- 125% becomes 1.25.
Fast mental checks
Use easy benchmark percentages to catch misplaced decimals. Ten percent is the number divided by 10. One percent is the number divided by 100. Five percent is half of ten percent.
- 20% of 250 should be twice 10% of 250.
- A result for 5% should be smaller than the result for 10%.
- More than 100% of a positive number should exceed the original number.
Finding what percent one number is of another
Reverse the relationship by dividing the part by the whole and multiplying by 100. If 50 is the part and 250 is the whole, 50 ÷ 250 × 100 equals 20%.
Frequently asked questions
How do I calculate 15% without a calculator?
Find 10% and 5%, then add them. For 200, those amounts are 20 and 10, so 15% is 30.
Can a percentage be above 100%?
Yes. A value equal to one and a half times the original is 150% of the original.