What is X% of Y?
=
30
15 × 200 ÷ 100 = 30
Percentage Calculator solves all common percentage problems in one tool: What is X% of Y? What percentage is X of Y? X is Y% of what number? What is the percentage change from X to Y? It also handles percentage increase, decrease, and compound percentage calculations. Results appear instantly with the formula shown so you can understand the math.
Percentage is a fundamental mathematical concept: percent means "per hundred," so 35% means 35 per 100, or 0.35 as a decimal. Percentage calculations appear in everyday contexts: calculating a 20% tip on a restaurant bill, understanding a 15% off sale, calculating your score as a percentage of total points, computing a year-over-year revenue change, and determining what percent of a budget has been spent.
Percentage change is often misunderstood. A 50% decrease followed by a 50% increase does not return to the original value — a $100 item drops to $50 (50% decrease), then rises to $75 (50% increase of $50). This is why investors must understand the asymmetry of percentage gains and losses — a 50% loss requires a 100% gain to recover.
20% tip on a $47.50 bill
Result: 20% of 47.50 = $9.50 tip / Total with tip: $57.00
Score: 73 out of 90
Result: 73 / 90 × 100 = 81.1% — your percentage score
Revenue change: $1.2M to $1.5M
Result: Percentage change = (1.5-1.2)/1.2 × 100 = 25% increase
What is the difference between percentage points and percent?
A change from 10% to 15% is 5 percentage points higher, but 50% relatively higher (5/10 = 0.5 = 50%). Political polls and economic reports often confuse these: 'approval rating rose 3 percentage points' is precise; 'rose 3%' is ambiguous. Percentage points describe absolute difference; percent describes relative difference.
Why is a 50% loss harder to recover from than a 50% gain is to lose?
Percentage changes compound from the current base. A 50% decrease on $100 gives $50. A 50% increase on $50 gives $75 — not $100. To recover from a 50% loss, you need a 100% gain. This asymmetry is why preserving capital is more important than maximizing gains in investing.
How do I calculate a percentage increase for a price?
New price = original × (1 + percent/100). A 20% increase on $50: $50 × 1.20 = $60. A 15% decrease: $50 × 0.85 = $42.50. To find the original price after a percentage increase, divide by (1 + percent/100): if $60 is after a 20% increase, original = $60 / 1.20 = $50.
What is CAGR (Compound Annual Growth Rate)?
CAGR is the rate at which an investment grows each year over a multi-year period: CAGR = (End Value / Start Value)^(1/years) - 1. A $100 investment that grows to $200 over 5 years has CAGR = (200/100)^(1/5) - 1 = 0.1487 = 14.87% per year. CAGR smooths out year-to-year volatility to show the steady growth rate.
How do I add tax to a price?
Multiply by (1 + tax_rate). For a 8.5% sales tax on a $50 item: $50 × 1.085 = $54.25. To find the pre-tax price from a tax-inclusive price: divide by (1 + tax_rate). $54.25 / 1.085 = $50. This is different from simply multiplying the tax-inclusive price by the tax rate.