Percentage calculator
Enter two numbers and get every percentage answer at the same time.
- Runs in your browser — nothing you enter is uploaded
- No sign-up, no quotas, free to use as often as you like
How it works
Percentage questions come in several shapes and people rarely know which one they want until they see it phrased. Rather than making you pick a mode first, this shows every answer for the two numbers you enter, labelled in plain words so you can take the line you actually need.
The six questions
What is A% of B. What percentage of B is A. The change from A to B. B increased by A%. B decreased by A%. And the plain difference. Between them they cover essentially every everyday percentage question.
Increase and decrease are not symmetrical
Going up 20% and then down 20% does not return you to where you started, because the second percentage is taken from the larger number. This trips people up constantly on discounts and tax.
Percentage change needs a starting point
The change from A to B is measured against A. If A is zero there is no meaningful percentage change — any increase from nothing is infinite — so that line says so instead of printing a misleading number.
Rounding
Answers are rounded to four decimal places, which is well beyond anything money or ordinary measurement needs while still showing that a number is not exact.
Percentage calculator — questions
Why does it show several answers?
Because “percentage” means several different calculations, and it is quicker to show all of them than to make you choose first.
Why does an increase then a decrease not cancel out?
The decrease is taken from the larger number, so it removes more than the increase added. This is normal and catches people out on discounts.
Why does it say a dash for percentage change?
Because the starting value is zero, and there is no meaningful percentage change from nothing.
Is anything I enter sent anywhere?
No. The calculation runs in the page.