Percentage calculator
Every everyday percentage question, written as a sentence you fill in.
How it works
- 01Find the sentence that matches your question.
- 02Type your numbers into the blanks. Commas and % signs are fine.
- 03Read the answer as you type, with the working shown underneath.
Questions
›How do I work out a percentage change?
Subtract the old value from the new one, divide by the old value, and multiply by 100. Going from 80 to 100 is a change of 20, and 20 ÷ 80 × 100 = a 25% increase.
›Why doesn't taking 20% off undo adding 20%?
Each percentage is taken of a different number. Adding 20% to 100 gives 120, but 20% of 120 is 24, so taking it off leaves 96. To find the price before a 20% tax, divide by 1.2 instead, which the reverse percentage calculator does for you.
›What is the difference between percent and percentage points?
Percentage points are the simple gap between two percentages, so a rate going from 4% to 5% rose by 1 point. Percent change compares that gap to the starting rate, which makes the same move a 25% increase.
›Can I use negative numbers or decimals?
Yes. Any number works, including decimals and negatives. Percentage change is measured against the size of the starting value, so -50 to -25 counts as a 50% increase.
›Is my data uploaded anywhere?
No. This tool runs entirely in your browser, and Rounder never sends what you type or drop in to a server, ours or anyone else's. Once the page has loaded, along with any AI model the tool uses, it even works offline.