Percentage Calculator
Answer all four of the common percentage questions — what is X% of Y, X is what percent of Y, percentage increase or decrease, and the original value before a change.
Your details
Result
Answer
- Working
- 15% of 200 = (15 ÷ 100) × 200 = 30
The formula
part = (percent ÷ 100) × whole- percent
- The rate, as a number out of 100
- whole
- The base value the percentage is taken of
- part
- The resulting amount
Every percentage question is this one equation rearranged. Given two of the three quantities you can always solve for the third: divide to find the percent, multiply to find the part, and divide the part by the rate to recover the whole.
Frequently asked questions
How do I work out a percentage of a number quickly?
Move the decimal point to get 10%, then scale. For 15% of 200: 10% is 20, 5% is half of that (10), so 15% is 30. For tips, 20% is just double the 10% figure.
Why isn't a 50% increase cancelled out by a 50% decrease?
Because the base changes. Start at 100, add 50% and you have 150. Take 50% off 150 and you have 75, not 100 — the second percentage was applied to the larger number. To reverse a 50% increase you need a 33.3% decrease.
What is the difference between percentage points and percent?
If a rate rises from 4% to 6%, that is a 2 percentage point increase but a 50% increase. News reports routinely conflate the two. Percentage points measure the absolute gap between two percentages; percent measures relative change.
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