Percentage Calculator
Answer the three everyday percentage questions. e.g. “What is 15% of 240?”
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Results update as you type. All calculation happens in your browser.
Methodology
Answer the three everyday percentage questions. This tool uses a standard, documented formula and runs entirely on your device.
Last reviewed January 2026 · Runs client-side
The three everyday percentage questions
Most percentage problems are one of three questions: what is X% of Y, what percent is X of Y, or how much did a value change. They look different but rest on the same relationship between a part, a whole, and a rate.
Getting comfortable with all three covers the vast majority of day-to-day percentage math, discounts, tips, test scores, tax, and growth figures all reduce to one of them.
How to use this calculator
- Pick the question type that matches what you're solving.
- Enter the two values.
- Read the answer along with the formula and the substituted numbers.
What the inputs mean
- Question type
- Switch between 'X% of Y', 'X is what % of Y', and percentage change.
- Values A and B
- The two numbers involved; their meaning depends on the question you chose.
15% of 240 is 36. Flip it around and 36 is 15% of 240. Change 240 to 276 and that's a 15% increase.
The formula, in plain terms
For 'X% of Y' multiply the rate by the whole; for 'what percent' divide the part by the whole; for change, divide the difference by the original.
Good to know
- Percentage points and percentages aren't the same, a move from 10% to 12% is 2 points but a 20% increase.
- Reversing a percentage change requires dividing, not subtracting the same percentage back.
Frequently asked questions
What's the difference between percent and percentage points?
Percentage points measure the raw gap between two percentages; a percentage change measures that gap relative to the starting value.
Last reviewed January 2026. This explainer is general information, not professional advice.