Percentage Calculator

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What is a percentage?

A percentage is simply a fraction of 100 — "20%" means 20 out of every 100. Percentages are everywhere: discounts, tips, tax, interest rates, and grades. This calculator handles the three questions people ask most: what is X% of Y, X is what percent of Y, and what is the percent change between two numbers. Pick a mode above and type — the answer appears instantly.

Formulas used

• X% of Y = (X ÷ 100) × Y. Example: 20% of 150 = 0.20 × 150 = 30.
• X is what % of Y = (X ÷ Y) × 100. Example: 30 is what % of 150 = 20%.
• % change = ((New − Old) ÷ |Old|) × 100. Positive means an increase, negative a decrease. Example: 100 → 130 = +30%.

Worked example

A jacket costs 150 with a 20% discount. Using "X% of Y": 20% of 150 = 30, so you save 30 and pay 120. Later the price rises from 100 to 130 — using "% change": (130 − 100) ÷ 100 × 100 = +30% increase. Try both in the calculator above.

Frequently asked questions

How do I calculate a discount quickly?

Use "X% of Y": enter the discount percent and the price. Subtract the result from the price to get what you pay. A 20% discount on 150 is 30 off — you pay 120.

What is the difference between percent and percentage points?

A "percent change" is relative; "percentage points" are absolute. Going from 10% to 15% is a 5 percentage point rise, but a 50% increase (5 ÷ 10). News headlines sometimes mix these up — now you won't.

Why does a 50% loss need a 100% gain to recover?

Because percentages compound on different bases. Lose 50% of 100 and you have 50; gaining 50% of 50 only gets you back to 75. You need a 100% gain on 50 to return to 100. This asymmetry is why investors fear drawdowns.

How do I reverse a percentage? (e.g. price before tax)

Divide by (1 + rate). If 120 includes 20% tax, the pre-tax price is 120 ÷ 1.20 = 100 — not 120 − 20% (which gives 96, wrong). The base matters.