WebToolsHUBHow to calculate percentages
- Pick the mode that matches your question: X% of Y, what percent X is of Y, percentage change, or add or subtract a percent.
- Type your two values — the result updates instantly as you type, with a plain-language sentence explaining it.
- In X% of Y mode, the table below the result shows 50%, 25%, 10%, 5% and 1% of your number for quick mental checks.
- For percentage change, enter the original value first and the new value second; the sign tells you increase or decrease.
- Use the quick-reference panel for the fraction shortcuts (1/4 = 25%, 1/8 = 12.5%) that cover most mental math.
Frequently Asked Questions
How do I calculate X percent of a number?
Multiply the number by the percentage and divide by 100 — 15% of 240 is 240 × 15 ÷ 100 = 36. The X% of Y mode does this instantly and shows the same answer for common percentages in the table below.
How is percentage change calculated?
Subtract the original value from the new value, divide by the absolute value of the original, and multiply by 100. Going from 80 to 92 is an increase of 15%; the original is the denominator, which is why change from 0 is undefined.
What is the difference between a percentage and percentage points?
Percentages are relative, points are absolute: if a rate moves from 4% to 5%, it rose by 1 percentage point but by 25 percent relative to its old value. Mixing the two is one of the most common reporting errors.
Is my data stored or sent anywhere?
No. Every calculation runs locally in your browser the moment you type, and nothing is saved, logged or transmitted — close the tab and nothing remains.
Why does x% of y equal y% of x?
Because both equal (x × y) ÷ 100 — multiplication is commutative. This symmetry is a genuine mental-math shortcut: 8% of 50 is easier to compute as 50% of 8, which is simply 4.