Percentage Calculator
Four percentage formulas in one place: X% of Y, what percent is X of Y, percentage change, and add/subtract a percentage. Results update as you type.
% of = —
is — % of
From to
Percentage change
How to use
X% of Y: Enter the percentage and the base number. Result updates instantly — e.g. 15% of 80 = 12.
X is what % of Y: Enter both values to find the percentage that X represents out of Y.
% change: Enter a starting value and ending value to find the percentage increase or decrease between them.
Add / subtract %: Enter a base number and a percentage to add or subtract. Useful for tax, discounts or markup calculations.
Use cases
- Calculating discounts: 20% off a $120 item = $96
- Working out VAT or sales tax on a price
- Tracking growth: revenue went from $40K to $52K — what is the % increase?
- Grading: a student scored 43/60 — what percentage is that?
- Finance: a stock moved from $150 to $112 — what is the % loss?
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 = (80 × 15) / 100 = 12. This calculator does it instantly — just enter the percentage and the number.
How do I calculate percentage change?
Percentage change = ((new value − old value) / |old value|) × 100. A positive result is an increase; a negative result is a decrease. For example, going from 50 to 75 is a 50% increase.
What percentage is X of Y?
Divide X by Y and multiply by 100. For example, 30 is what percentage of 120? (30 / 120) × 100 = 25%. Use the "X is what % of Y" tab for this.
How do I reverse a percentage? (find the original value)
If a value after a percentage increase is known, divide it by (1 + percentage/100). For example, if 120 is 20% more than the original, the original = 120 / 1.20 = 100. Use the "reverse %" tab.
How do I add or subtract a percentage from a number?
To add P% to X: result = X × (1 + P/100). To subtract: result = X × (1 − P/100). For example, adding 20% to 50: 50 × 1.20 = 60. Subtracting 20% from 50: 50 × 0.80 = 40.
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