Percentage Calculator
Calculate percentages, ratios, and percentage change.
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About Percentage Calculator
Discounts, tips, exam scores and price moves all come down to three questions about percentages. Pick the one you are asking, fill in the two boxes, and the answer appears as soon as both hold numbers, with a line below it that spells out the calculation. Increases in percent change carry a plus sign, decimals and negative numbers are accepted, and very small or very large results are rounded sensibly instead of showing false precision.
Features
- Three modes: percent of, what percent, percent change
- Result updates as soon as both numbers are filled in
- Signed percent change with a plus sign on increases
- Four decimals for normal values, six significant digits for tiny ones
- Plain error messages for a zero total or a zero starting value
Limitations
- Percent change cannot start from zero, because the change is divided by the starting value, so a rise from nothing has no percentage here.
- It handles one pair of numbers at a time and keeps no history of earlier answers.
- Results are rounded for display, and very large results switch to exponent notation.
How it works
- Choose a calculation type: X% of Y, X is what % of Y, or % change X to Y.
- Fill in the two boxes. Their labels follow the type, for example Percentage and Of number, or From and To.
- Check the question line above the boxes, which repeats your numbers as a sentence.
- Read the answer in the Result card, with the full calculation written under it.
- Use Copy result to put the value on the clipboard, or Reset to clear both boxes.
Example input
What is 15% of 240?Frequently asked questions
- It is the new value minus the old one, divided by the absolute value of the old one, times 100. Going from 150 to 100 gives -33.3333%. Because the start is taken as an absolute value, moving from -50 to -25 reads as +50%, a rise of half the distance from zero.
- In the X is what % of Y mode the second box is the total, and a total of zero has no percentage. The percent change mode has a similar rule: it shows that the starting value cannot be zero, since there is nothing to measure the change against.
- Values of 1 or more show up to four decimals, so 1 is what % of 3 reads 33.3333%. Values below 1 keep six significant digits, so a tiny share such as 0.0000001 of 1 shows as 0.00001% instead of rounding to zero. Past 1e15 the result switches to exponent form.
- Yes to both, in all three modes. Type 2.5 in the Percentage box to find 2.5% of a figure. If either box is empty or is not a number, nothing is calculated and the page just asks for both numbers.
- No. The sum is done by a script on the page, and the values you enter are not sent to a server. The Share button copies only the address of the tool, not your numbers, so a shared link opens a blank calculator.
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