Percentage Calculator
Calculate a percentage of a value, a part’s share of a total, or the percentage change between two values. Choose the calculation before entering your numbers.
- Find A percent of B
- Express a part as a percentage
- Measure increase or decrease from a starting value
Find a percentage amount
For 15% of 200, multiply 200 by 15/100 to get 30. Use this mode when the rate is already known.
Find a proportional share
Divide the part by the total and multiply by 100. A zero total has no defined percentage and is rejected.
Compare a start and an end
Percentage change uses the difference relative to the absolute starting value. A zero starting value cannot supply a meaningful denominator.
Distinguish points from percent
Moving from 20% to 25% is a rise of 5 percentage points, but a 25% relative increase. Choose the interpretation your comparison needs.
Percentage Calculator FAQs
Yes. A part larger than the comparison total produces a share above 100%.
Relative percentage change divides by the starting magnitude; division by zero is undefined.
The increase is 20 relative to a starting value of 80, so 20 ÷ 80 × 100 = 25%. Select change from A to B and enter 80 then 100. Reversing them gives a 20% decrease because the starting value becomes 100.