Percentage Calculator

A percentage calculator works out a share of a number as hundredths — a percentage of a value, what percentage one value is of another, or how much a value has risen or fallen in percentage terms.

Four questions come up again and again: a percentage of an amount, one amount as a percentage of another, and a rise or a fall expressed as a percentage. This calculator answers whichever one you pick and shows the arithmetic, so you can check it rather than take it on trust.

1. Choose the question you want answered.
2. Enter the two values. The help text under each box says what X and Y mean for the question you picked.
3. Read the answer and the working underneath it.

X% of Y            → Y × X ÷ 100
X as a % of Y      → X ÷ Y × 100
change from X to Y → (Y − X) ÷ |X| × 100

Percentage change is measured against the starting value, which is why a rise from 50 to 100 is 100% but the fall back from 100 to 50 is 50%.

A ₹2,400 item is discounted by 15%.

The discount is ₹360 and you pay ₹2,040.

• A rise and the fall that undoes it are not the same percentage. Going from 100 to 150 is a 50% increase; going back from 150 to 100 is a 33.33% decrease.
• Percentage change is undefined when the starting value is zero, so the calculator asks you to correct that rather than showing infinity.