Everyday Calculators
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Open toolPercentage Calculator
Percentages show up everywhere — discounts, tax, tips, exam scores, price rises — and they are surprisingly easy to get wrong in your head. This free percentage calculator covers the three questions people actually ask: what is X% of a number, one number is what percent of another, and what is the percentage increase or decrease between two numbers. Fill in any panel and get the answer instantly, with the formula shown in the FAQs below so you can check the maths yourself. It is handy for shopping discounts, working out sales tax, splitting bills, and checking how much a price or a salary has really changed.
What is X% of Y?
Answer: —
X is what percent of Y?
Answer: —
Percentage increase or decrease
Answer: —
All three panels update as you type — no button to press.
How to use this tool
- Pick the calculation you need — all three are on the page.
- Type your two numbers; results update as you type.
- Read the answer plus the one-line formula behind it.
- Use the change mode for price rises, discounts and growth.
Worked example
20% of 250 is 50; 50 is 20% of 250; and going from 80 to 100 is a 25% increase — all three answers from one page.
Frequently asked questions
How do I calculate what percent of a number something is?
Divide the part by the whole, then multiply by 100. For example, 45 out of 180 is 45 ÷ 180 = 0.25, which is 25%. That is the second panel of this calculator. The reverse — finding a percentage of a number — is the number multiplied by the percentage divided by 100: 20% of 250 is 250 × 20 ÷ 100 = 50.
How is percentage change calculated?
Subtract the old value from the new value, divide the difference by the old value, and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 = 25% increase. Going from 100 down to 80 is (80 − 100) ÷ 100 = a 20% decrease — note the two are not the same number, because the starting point differs.
What is the difference between percent and percentage points?
If an interest rate rises from 4% to 5%, that is an increase of one percentage point — but a 25% relative increase in the rate itself. News reports often mix the two up. This calculator's change panel always gives the relative change (the 25% figure), which is what matters for prices, salaries and bills.
How do I work out a discount price quickly?
Multiply the price by (100 − discount) ÷ 100. A $250 item at 20% off is 250 × 0.8 = $200. Or use the first panel: 20% of 250 is $50 off, so you pay 250 − 50 = $200. For business pricing rather than shopping, the profit margin calculator handles margins and markups, which are related but not the same thing as a simple percentage.
Related tools: price work with the profit margin calculator, or work out grades with the grade calculator.