Percentage Calculator
Work out percentages, percentage change, and X is what % of Y.
Choose a calculation
Result
30.00
20.00% of 150.00
What does this mean?
Percentages express a number as a fraction of 100. This calculator covers the three questions people ask most: what a percentage of a number is, what percentage one number is of another, and how much a value changed in percentage terms.
The formulas
- X% of Y = (X ÷ 100) × Y
- X is what % of Y = (X ÷ Y) × 100
- % change = ((new − old) ÷ |old|) × 100
A quick example
20% of 150 is 30. A price that rises from 150 to 180 is a 20% increase, while a drop from 150 to 120 is a 20% decrease. Notice that a 20% rise followed by a 20% fall does not return you to the start — percentages always apply to the current value.
Frequently asked questions
How do I calculate a percentage of a number?+
Divide the percentage by 100 and multiply by the number. For example, 20% of 150 is 0.20 × 150 = 30.
How do I work out percentage increase or decrease?+
Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is an increase; a negative result is a decrease.
Why isn't a 20% rise then a 20% fall back to the start?+
Each percentage applies to the current amount, not the original. A 20% rise from 100 gives 120, and a 20% fall from 120 gives 96 — lower than where you began.
Can I use this for discounts and tips?+
Yes, but for shopping and dining the discount and tip calculators give a clearer breakdown with currency and totals.