Percentage Calculator
Five quick percentage calculators, each with the working written out.
What is% of?
is what percent of?
Percentage change fromto
by%
A value isafterof%. What was it before?
Quick reminders
- Per cent means "for each hundred": 15% is 15 out of every 100, or 0.15.
- To take 20% off, multiply by 0.8. To add 20%, multiply by 1.2.
- Going up 25% and then down 25% does not get you back: 100 rises to 125, then falls to 93.75.
- From 10% to 15% is a rise of 5 percentage points, but a 50% increase.
How to use the Percentage Calculator
- Pick the question you are asking: a share of a number, a share as a percentage, the change between two values, a mark-up or discount, or the price before a change.
- Type your numbers into the sentence. Decimals, thousands separators and currency signs are all fine.
- Read the answer underneath, together with the working written out step by step.
- Set a fixed number of decimal places if you need one, then copy the result.
About this tool
Most percentage questions have one of five shapes, and this page has a small calculator for each: what is 15% of 80, what percent is 45 of 60, how big is the change from 40 to 50, what does 200 become after a 15% rise or fall, and what was the price before a 20% discount brought it down to 80. Each one updates as you type and spells out the arithmetic underneath, so you can follow the method rather than just trust a number.
The sums are done with exact decimals instead of the binary floating-point arithmetic that most calculators and spreadsheets use. That is why 0.07 × 100 comes out as exactly 7 here, and why 2.675 rounded to two places gives 2.68 rather than 2.67. Division is the only step that can run on without end; when that happens the result is rounded and marked as rounded.
A common slip is to reverse a percentage change by applying the same percentage the other way. A price that rose by 25% does not come back down with a 25% cut: 100 becomes 125, and 125 less 25% is 93.75. The last calculator handles that properly by dividing by the growth factor instead.
Frequently asked questions
What is the difference between percentage change and percentage points?
Percentage change compares the new value with the old one, so going from 10% to 15% is a 50% increase. Percentage points are the plain difference between two percentages, which in that case is 5 points. The change calculator here gives the percentage change.
How is a negative starting value handled in the change calculator?
The difference is divided by the size of the starting value, ignoring its sign. Going from -50 to -25 is therefore a 50% increase, because the value moved up by half of 50. A change that starts from exactly 0 has no percentage at all.
Why is a result sometimes labelled as rounded?
A division such as 1 ÷ 3 never ends, so its result is cut to six decimal places, or to the number of places you chose, and labelled so you know it is not exact. Every other step is exact.
Can I type amounts with commas or currency signs?
Yes. Spaces, currency symbols and percent signs are ignored. A comma followed by three digits, as in 1,250, is read as a thousands separator; any other lone comma is read as a decimal comma, as in 12,5.
Are the numbers I enter stored or sent anywhere?
They are not sent to any server; the arithmetic runs inside this page. Your last values are remembered in this browser only, so they are still there when you come back, and Reset clears them.