Percentage Calculator

Percentages show up everywhere — shop discounts, exam marks, tips, tax and salary rises — and a small slip in the maths can cost real money. This free percentage calculator answers the three questions people actually ask: what is X% of Y, what percentage is X of Y, and how much did a value rise or fall in percent. Type your numbers and the answer appears instantly, with every step shown.

Everything runs in your browser, so your numbers never leave your device. When you need a monthly payment figure next, try the Loan EMI Calculator, or check a date-based result with the Age Calculator — both free, with the same step-by-step working.

The three percentage formulas

A percentage is a fraction out of 100 — from the Latin per centum, “by the hundred”, so 15% means 15 out of every 100. All three modes below use that one idea, rearranged.

1. X% of Y

Result = (X ÷ 100) × Y. Worked example: 15% of 200 = (15 ÷ 100) × 200 = 0.15 × 200 = 30. Use it for discounts, tips, tax and exam scores.

2. X is what % of Y

Percentage = (X ÷ Y) × 100. Worked example: 30 is (30 ÷ 200) × 100 = 15% of 200. Use it when you know the part and the whole — for example 42 out of 60 is 70%.

3. Percentage increase or decrease

Change % = ((B − A) ÷ A) × 100. Worked example: from 80 to 100 gives (20 ÷ 80) × 100 = +25%, a 25% increase. A negative answer means a decrease: from 200 to 150 is −25%. The starting value A is always the base.

Common percentages at a glance

Watch out for the classic trap: a 50% rise followed by a 50% fall does not return to the start. $100 up 50% is $150, and 50% off $150 is $75 — the second percentage is taken from a bigger base.