Percentage Calculator
Pick the question, type two numbers and read the answer as you type. The calculator covers the six everyday cases of percentage arithmetic and shows the formula behind each result.
About this tool
Every Percentage Question in One Place
Percentages come up in prices, VAT, discounts, salaries, statistics and grades. The calculator answers each kind of question without a formula sheet.
Six Kinds of Question
X % of Y, X as a percentage of Y, the base value, the percentage change, adding or subtracting a percentage and the value before a change.
Formula Included
Each answer shows the calculation with your numbers, so you can check it or write it down.
Difference and Factor
For changes, markups and discounts you also see the absolute difference and the growth factor.
How to use it
- Choose what you want to calculate, for example “Percentage change”.
- Type the two numbers the question asks for.
- For markups and discounts, choose Increase or Decrease.
- Read the answer, the difference and the formula.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100: 20 % of 150 is 150 × 20 ÷ 100 = 30.
How do I calculate the percentage change?
Subtract the old value from the new one, divide by the old value and multiply by 100: from 80 to 100 is (100 − 80) ÷ 80 × 100 = +25 %. Going back from 100 to 80 is −20 %, not −25 %, because the base is different.
How do I get the original price before a discount or VAT?
Divide by the factor instead of subtracting the percentage: 119 € including 19 % VAT is 119 ÷ 1.19 = 100 €; 75 € after 25 % off was 75 ÷ 0.75 = 100 €.
Is my financial data uploaded to any server?
No. Every calculation, PDF and XML file is produced inside your browser tab with JavaScript and WebAssembly. Nothing is uploaded, stored or logged — the tool also keeps working offline.