Percentage Calculator
Three percentage tools in one: X% of Y, X as a % of Y, and percentage change between two values.
Percentages, without the headache
Percentages are everywhere — discounts, exam scores, interest rates, tax, statistics in the news — yet they trip up almost everyone at times, usually because three different questions hide behind the same symbol. This calculator separates them cleanly: a percentage of a number, one number as a percentage of another, and the percentage change between two numbers.
Worked examples: 15% of 240 is 36. A score of 45 out of 180 is 25%. And a price rising from 80 to 100 is a 25% increase — note the base matters: falling back from 100 to 80 would be only a 20% decrease, because the starting point changed.
That asymmetry is the most common percentage trap. Increases and decreases of the same 'percent' do not cancel out — after a 50% fall you need a 100% rise to get back to where you started.
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 240 = 240 × 15 ÷ 100 = 36. A quick mental trick: find 10% by moving the decimal point, then build from there.
How is percentage change calculated?
Percentage change = (new value − old value) ÷ old value × 100. A move from 80 to 100 is (20 ÷ 80) × 100 = a 25% increase. If the result is negative, it is a decrease.
What is the difference between percent and percentage points?
If an interest rate rises from 4% to 5%, that is a 1 percentage point increase — but a 25% relative increase. Confusing the two is a common source of misleading headlines.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. If you scored 45 out of 60, that is 45 ÷ 60 × 100 = 75%.