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Tip Calculator
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Percentage Calculator
Find what percentage one number is of another, calculate a percentage of a value, or determine the percentage change between two numbers.
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How to use the Percentage Calculator
Choose your calculation type
Select one of the three tabs: 'Percentage of a Number' (e.g. 15% of 85), 'Number as a Percentage' (e.g. 40 is what % of 320?), or 'Percentage Change' (e.g. from 50 to 65).
Enter your two numbers
Type the values into the two input fields. The result updates instantly as you type — no need to press enter or click calculate.
Read the result and formula
The answer appears in the green result card. Below it you'll see the formula used so you can understand the calculation and reproduce it yourself.
Copy the result
Use the Copy button on the result card to copy a formatted answer to your clipboard, ready to paste wherever you need it.
About this Percentage Calculator
Percentages are one of the most useful concepts in everyday maths, yet many people still struggle with them. Our free percentage calculator handles three common types of calculation in one place. First, "percentage of a number" — the most frequent task, such as calculating a 20% discount off a sale price or working out how much tax to add to an invoice. Second, "number as a percentage" — used when comparing scores or proportions, like "I got 68 out of 80, what percentage is that?" Third, "percentage change" — essential for finance, science, and performance reporting, showing how much something has increased or decreased relative to its original value. To calculate a percentage manually: divide the percent by 100 and multiply by the number. For a percent increase calculator, subtract the old value from the new, divide by the old value, and multiply by 100. A positive result is an increase; negative is a decrease. Our calculator shows the formula used for every result so you can verify your working or learn how to calculate percentage change yourself next time.
Frequently Asked Questions
Divide the part by the whole and multiply by 100. For example, 25 out of 200 = (25 ÷ 200) × 100 = 12.5%. Our calculator does this automatically.
Subtract the original value from the new value, divide by the original value, then multiply by 100. Example: going from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.
To find 20% of a number, multiply it by 0.20 (or divide by 5). For example, 20% of 350 = 350 × 0.20 = 70. Use our calculator for any percentage instantly.
Percentage change = ((New Value − Old Value) ÷ |Old Value|) × 100. If the result is positive it's an increase; negative means a decrease. For example, a price rising from £80 to £100 is a 25% increase: ((100 − 80) ÷ 80) × 100 = 25%.
Multiply the original price by the discount percentage as a decimal to find the discount amount, then subtract. For example, 20% off £150: £150 × 0.20 = £30 discount → £120 final price. Use the 'Percentage of a Number' tab in our calculator.