Free percentage calculator with three modes — find what percent of a number is, calculate percent change between two values, or compute what percentage one number is of another. Instant discount calculator and percent change tool with no signup needed.
Three calculation modes in one tool
Percentages appear in nearly every financial and everyday context — retail discounts, sales tax, restaurant tips, investment returns, grade scores, interest rates, and statistical data. This percentage calculator handles all three core calculations in one place. Mode 1 ("What is X% of Y?") finds a percentage of any number — use it for discounts, tax amounts, and tips. Mode 2 ("X is what % of Y?") finds what percentage one number represents of another — useful for test scores, market share calculations, and budget analysis. Mode 3 ("% Change from X to Y") calculates the percentage increase or decrease between two values — critical for understanding price changes, investment returns, and business growth rates.
One of the most commonly confused percentage concepts is the asymmetry of gains and losses. If a stock price drops from $100 to $80, that is a 20% decrease. But to recover from $80 back to $100, you need a 25% increase — not 20%. This asymmetry is why financial advisors emphasize avoiding large losses: a 50% portfolio drop requires a 100% gain just to break even. Similarly, a store advertising "50% off then an additional 20% off" is not giving you 70% off — it's 50% off, then 20% off the reduced price, which equals a 60% total discount. Understanding how percent change and compound discounts work saves real money.
A 30% discount on a $150 item saves $45 — the sale price is $105. To find the discount amount: multiply the original price by the percentage (150 × 0.30 = 45). For stacked discounts, apply them sequentially: 20% off $100 = $80, then 10% off $80 = $72 total (not 70% of $100).
An 8.5% sales tax on a $200 purchase adds $17, bringing the total to $217. Use the percentage calculator to find the exact tax on any amount. Sales tax rates vary from 0% (Delaware, Oregon) to over 10% in some California cities — always verify the rate for your location.
Percent change = (New − Old) / Old × 100. A home value rising from $350,000 to $420,000 is a 20% increase. From $420,000 back to $350,000 is a 16.67% decrease — different percentages for the same dollar amount because the base changed. Direction matters in percent change calculations.
For a 20% tip on an $85 restaurant bill: 20% of $85 = $17 tip, total $102. For 15%, it's $12.75 tip, total $97.75. A quick mental shortcut: find 10% (move the decimal left one place), then double it for 20%, or add half for 15%. Works on any bill amount in seconds.