Percentage Calculator
Calculate percentages instantly: find X% of a number, work out what percent one number is of another, or calculate percentage increase and decrease.
Result
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Percentages show up everywhere, from calculating a restaurant tip to figuring out a discount at checkout or tracking how much a stock price has moved. This calculator handles the three most common percentage problems people search for: finding a percentage of a number, finding what percentage one number represents of another, and calculating the percentage increase or decrease between two values. Enter your numbers below and get an instant, accurate result with the full working shown.
How to use this calculator
- Choose the calculation mode that matches your question: 'X% of Y', 'X is what % of Y', or '% increase/decrease'.
- Enter the required numbers into the input fields.
- The result updates instantly as you type — no need to click a button.
- Use the result for budgeting, grading, discounts, tips, or any other percentage-based task.
How percentages are calculated
A percentage is simply a fraction of 100. To find X% of a number Y, multiply Y by (X / 100). For example, 20% of 50 is 50 × 0.20 = 10.
To find what percentage X is of Y, divide X by Y and multiply by 100: (X / Y) × 100. For example, 15 is what percent of 60? (15 / 60) × 100 = 25%.
To find the percentage increase or decrease between two numbers, subtract the original value from the new value, divide by the original value, then multiply by 100: ((New − Original) / Original) × 100. A positive result is an increase; a negative result is a decrease.
Example: Finding a percentage of a number
You want to calculate a 15% tip on a $42.00 bill.
15% of 42 = 42 × 0.15 = $6.30 tip.
Example: Percentage increase
A product's price rose from $80 to $92.
Increase = ((92 − 80) / 80) × 100 = 15% increase.
Frequently asked questions
How do I calculate a percentage increase between two numbers?
Subtract the original number from the new number, divide the result by the original number, then multiply by 100. For example, going from 50 to 65 is ((65 − 50) / 50) × 100 = 30% increase.
How do I find what percentage one number is of another?
Divide the part by the whole, then multiply by 100. For example, 25 out of 200 is (25 / 200) × 100 = 12.5%.
Can percentages be negative?
Yes. A negative result in a percentage change calculation means a decrease rather than an increase — for example, a value dropping from 100 to 80 is a −20% change.
How do I calculate a percentage discount?
Multiply the original price by the discount percentage (as a decimal) to find the amount saved, then subtract that from the original price. A 20% discount on $50 saves $10, making the final price $40.
Why do my percentage calculations need rounding?
Percentages often produce repeating decimals (e.g. 1/3 = 33.333...%). This calculator rounds to two decimal places for readability while keeping the underlying calculation precise.