Calculators
Percentage Calculator
Calculate X% of Y, what percent X is of Y, or the increase/decrease between two values.
Enter values and press Calculate.
What is a percentage calculator?
A percentage calculator answers the three questions people ask most often about percentages: what is X percent of a number, what percentage one number is of another, and how much something grew or shrank in percentage terms. Instead of reaching for a formula or a spreadsheet, you pick the calculation type, enter two numbers, and get an instant answer. It is useful for students, shoppers, freelancers, and anyone who deals with numbers daily.
How to use this tool
- Choose the calculation type from the dropdown: "X% of Y", "X is what percent of Y", or "increase / decrease".
- Enter the two numbers in the labelled fields. The labels update automatically to match the mode you picked.
- Press Calculate to see the result displayed prominently, with the full working shown underneath.
- Use Clear to reset the fields and start a new calculation.
Key features
- Three calculation modes in one place, with labels that adapt to each mode so you never mix up the inputs.
- Handles percentage increase and decrease, clearly telling you whether the change is growth or a drop.
- Safe handling of edge cases: dividing by zero or leaving a field empty shows a helpful hint instead of an error or a wrong number.
- Results are formatted with thousands separators and rounded to two decimals for easy reading.
- Runs entirely in your browser — nothing you type is sent to any server.
Common use cases
- Shopping: working out a sale price or checking that a store's "30% off" claim is correct.
- Finance: calculating interest portions, tax amounts, tips, or investment returns.
- Academics: converting marks to percentages, or finding the percentage change between two exam scores.
- Business: measuring revenue growth month over month, or what share one product is of total sales.
- Freelancing: quickly adding a service charge or discount percentage to an invoice total.
Practical tips
- For "X is what percent of Y", the second number (Y) is always the whole — the number you are comparing against.
- Percentage change is not symmetric: a 50% drop needs a 100% gain to recover, because the base changes.
- Do not confuse a percentage change with percentage points: going from 10% to 15% is a 5 percentage-point rise, but a 50% increase.
- When comparing prices across shops, convert every discount to the final price before comparing — a bigger percentage off a higher price can still cost more.
Frequently Asked Questions
How do I calculate X percent of a number?
Multiply the number by X and divide by 100. For example, 20% of 500 is (20 × 500) ÷ 100 = 100. Choose the 'X% of Y' mode in the tool and it does this instantly.
How do I find what percentage one number is of another?
Divide the first number by the second and multiply by 100. For example, 45 out of 150 is (45 ÷ 150) × 100 = 30%. Use the 'X is what percent of Y' mode.
How is percentage increase or decrease calculated?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase and a negative one is a decrease.
What is the difference between percent and percentage points?
A move from 10% to 15% is a 5 percentage-point rise, but a 50% increase relative to the starting 10%. The tool reports the relative change.
Is my data sent anywhere when I use this calculator?
No. All calculations happen locally in your browser with JavaScript, so your numbers never leave your device.