Percentage Calculator
Calculate discounts, increases, percentages of values, and percentage changes between numbers.
The percentage calculator brings together the most common everyday percentage calculations: finding out how much X% of a value is, calculating a discounted or increased price, and measuring the percentage change between two numbers. These calculations show up constantly in shopping, salary negotiations, investment analysis, and even in the news — understanding the mechanics behind them helps you read any percentage-based situation more clearly. Pick the calculation type, fill in the values, and watch the result update automatically.
How to use
- Choose the calculation you need: percentage of a value, discount, increase, or change between two values.
- Fill in the fields that appear for that calculation.
- The result updates automatically as you type, no button needed.
Worked example
A store advertises a jacket for $250.00 with a 30% Black Friday discount. Using "Discount" mode, with original value $250.00 and percentage 30%, the calculator shows the discount is $75.00 (250 × 30 ÷ 100), and the final price comes to $175.00 (250 − 75). This is the same calculation used to check whether a promotion is actually a good deal, or to compare different percentage discounts across stores.
Frequently asked questions
How do I calculate how much X% of a value is?
Multiply the value by the percentage and divide by 100. For example, 15% of 200 is (200 × 15) ÷ 100 = 30.
How do I calculate a discounted price?
Subtract from the original value the percentage discount applied to it. A $100 item with a 20% discount costs $80, a $20 saving.
How do I calculate the percentage change between two values?
Subtract the initial value from the final value, divide by the initial value, and multiply by 100. A value going from 100 to 120 changed by +20%.
Is a 20% discount followed by another 10% discount the same as 30% off?
No. Successive discounts each apply to the value already reduced by the previous one, so the total is less than the simple sum. A $100 item with a 20% discount becomes $80; applying another 10% to $80 gives a final price of $72 — a total reduction of 28%, not 30%.
Does increasing by 50% and then decreasing by 50% return to the original value?
No, and this is a common mistake. A $100 value that increases by 50% becomes $150. Decreasing $150 by 50% gives $75, not $100 again — because the 50% decrease applies to the larger value ($150), not to the original one.
Why does the percentage change sometimes come out negative?
Because the final value is smaller than the initial one. In "Percentage change" mode, a value dropping from 100 to 80 has a change of −20%, indicating a decrease — the negative sign is part of the result and shows the direction of the change, not a calculation error.