Percentage Calculator
Three percentage calculators in one: X% of Y, X is what % of Y, and percentage change.
100% private. Your files never leave your device.
15% of 80 = 12
Formula: 80 × 15 ÷ 100 = 12
About this tool
Solve the three most common percentage problems without wrestling with formulas. The first mode answers "what is X% of Y", which covers tips, discounts, and tax. The second answers "X is what percent of Y", which covers test scores and progress toward a goal. The third computes the percentage change between two values and correctly tells increases from decreases, which is what you need for price changes, weight loss, and growth figures. Every result updates instantly as you type and shows the formula used, so the tool doubles as a homework checker.
How to use
- 1Pick the mode that matches your question using the three tabs.
- 2Enter your two numbers. The result appears instantly, no button needed.
- 3Read the formula shown beneath the result to understand or double-check the math.
- 4Switch tabs at any time. Each mode keeps its own inputs.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 80 is 80 x 15 / 100 = 12.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 45 out of 60 is 45 / 60 x 100 = 75%.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 50 to 65 is (65 - 50) / 50 x 100 = a 30% increase.
Is percentage change the same as percentage points?
No. Moving from 10% to 15% is a rise of 5 percentage points, but a 50% relative increase. This calculator reports the relative change between the two values you enter.
More student tools
GPA Calculator
Work out your GPA on the 4.0 scale. Add courses, credits, and grades.
Open toolAge Calculator
See exact age in years, months, days, hours, minutes, and seconds.
Open toolUnit Converter
Convert length, weight, temperature, and file size. Metric and imperial together.
Open tool