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Percentage Calculator
Percent of a number, percent share and percent change.
Use the Percentage Calculator tool
What this percentage calculator does
Percentage Calculator covers the three questions people actually ask. “What is 15% of 240?” is a simple multiplication. “36 is what percent of 240?” divides one number by the other. “What is the percentage change from 240 to 300?” measures growth or decline relative to the starting value.
Each mode displays the formula alongside the answer, so you can reuse the method in a spreadsheet. Results are rounded for display but computed at full precision, which matters for tax, discount and margin calculations where small rounding differences accumulate.
Why use it
- Work out a discount or a tip without guessing.
- Compare month-on-month growth in sales or traffic.
- Check a quoted percentage against the underlying numbers.
How to use it
- 1Choose the question you are answering.
- 2Enter the two values.
- 3Read the result and the formula used.
- 4Copy the answer with one click.
Worked examples
Percent of a number
Input
15% of 240
Output
36 · formula: 240 × 0.15
Percentage change
Input
From 240 to 300
Output
+25% · formula: (300 − 240) ÷ 240 × 100
Common mistakes
- Applying the percentage change to the new value instead of the original value.
- Confusing percentage points with percent — going from 5% to 7% is a 2-point rise but a 40% increase.
- Adding percentages in sequence; two 10% discounts are not a 20% discount, but 19%.
Frequently asked questions
How do I calculate a percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. A result of 25 means a 25% increase.
Why is a 20% discount followed by a 10% discount not 30%?
The second discount applies to the already reduced price. 100 → 80 → 72, which is a 28% total reduction.