Percentage Calculator

Which Calculation Do You Need?

X% of Y finds a portion of a value. Percentage increase/decrease finds how much a value changed, relative to its original value. Percentage difference compares two values symmetrically (neither is treated as "original"). Find the original value works backward from a final value and a known percentage change.

How to Use It

1. Choose the calculation type that matches what you need.
2. Enter the relevant numbers.
3. View the result along with the formula used.

Handling Division by Zero

Percentage change from zero is undefined (you can't express a change relative to nothing) - this tool clearly reports that case rather than showing an incorrect number like Infinity or NaN.

Worked Examples

• X% of Y: 18% GST on ₹2,500 is 2,500 × 18 ÷ 100 = ₹450.
• Percentage increase: a price rising from 800 to 1,000 is (1,000 - 800) ÷ 800 × 100 = 25% increase.
• Percentage decrease: traffic falling from 5,000 to 4,000 visits is (4,000 - 5,000) ÷ 5,000 × 100 = -20%.
• What percent is X of Y: scoring 42 out of 60 is 42 ÷ 60 × 100 = 70%.
• Original value: a jacket costs ₹1,200 after a 20% discount, so the original price was 1,200 ÷ 0.8 = ₹1,500.

Two Common Traps

Increases and decreases are not symmetrical. A 50% drop followed by a 50% rise does not get you back: 100 → 50 → 75.

Percent vs percentage points. An interest rate going from 4% to 5% rose by 1 percentage point, but by 25 percent.

Quick Mental Shortcuts

• 10% - move the decimal point one place left.
• 5% - half of 10%.
• X% of Y equals Y% of X: 8% of 50 is the same as 50% of 8, which is 4.

For remainders, try the Modulo Calculator; for very large or small numbers, the Scientific Notation Converter.