Three percentage questions, one tool
Most everyday percentage problems fall into three types, and this calculator handles all of them. Finding a percent of a number (what is 25% of 200?), finding what percent one number is of another (40 is what percent of 200?), and finding the percentage change between two numbers (from 200 to 250 is what increase?).
The formulas
- A% of B = A ÷ 100 × B
- A is (A ÷ B × 100)% of B
- change = (B − A) ÷ A × 100
Where you'll use it
Percentages are everywhere: working out a discount or a tip, a tax rate, exam scores, interest, or how much a price or audience has grown. The percentage-change mode is especially handy for spotting growth or shrinkage — a positive result is an increase, a negative one a decrease.
Frequently asked questions
How do I find a discount?
Use 'A% of B' with A as the discount percent and B as the price, then subtract from the price.
What does a negative change mean?
A decrease. From 200 to 150 is −25%.
Is my data private?
Yes — everything is calculated in your browser.