Percentage Calculator
Find any percentage instantly — what is X% of Y, percentage difference, increase/decrease, and more. Six calculation modes in one tool.
Calculation Type
Result
Percentage Formulas Reference
X% of Y: Result = (X / 100) × Y
X is what % of Y: Result = (X / Y) × 100
% Change from A to B: Result = ((B − A) / |A|) × 100
Original value: Original = Value / (1 + change%/100)
Everything About the Percentage Calculator
Every percentage formula you need, common use cases, and the mental math shortcuts that save time every day.
How It Works
- Select your calculation mode from the tabs
- “X% of Y” — find the actual amount (e.g. 15% of $60 = $9)
- “X is what % of Y” — find the proportion (e.g. 30 is 25% of 120)
- “% change” — find growth or decline between two numbers
- “Reverse” — find original value when you know part and percentage
The Formula
X% of Y = Y × X ÷ 100
X is ??% of Y = (X ÷ Y) × 100
% Change = (New − Old) ÷ Old × 100
Y from X at P% = X ÷ (P ÷ 100)
“Per cent” = Latin for “per 100”. All percentage calculations reduce to a ratio out of 100.
Pro Tips
- “Percentage points” ≠ “percent”: 20% → 25% = +5 pp but +25% relative increase
- Quick 15% tip: take 10% (move decimal left one digit), then add half of that
- +50% then −50% ≠ 0%: $100 → $150 → $75 — always asymmetric
- To add tax: multiply by (1 + rate), e.g. add 8.5% sales tax = price × 1.085
Frequently Asked Questions
What is the basic percentage formula? +
Three core formulas cover most percentage questions: (1) Find percent: (Part ÷ Whole) × 100. Example: 45 out of 180 = 25%. (2) Find the part: (Percentage × Whole) ÷ 100. Example: 30% of $250 = $75. (3) Find the whole: (Part × 100) ÷ Percentage. Example: $60 is 15% of what? $60 × 100 ÷ 15 = $400. These three calculations cover shopping discounts, test scores, tips, tax calculations, and most everyday math.
How do I calculate percentage change? +
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. Positive = increase, negative = decrease. Example: stock went from $50 to $65 = ((65−50)÷50)×100 = 30% increase. For a decrease: $100 to $75 = ((75−100)÷100)×100 = −25%. Caution: a 50% drop then a 50% gain does NOT return you to the original value — $100 −50% = $50 − then +50% = $75, not $100.
What is the difference between percentage points and percent? +
This distinction is critical in finance and reporting. If an interest rate rises from 2% to 3%, that is a 1 percentage point increase, but a 50% relative increase in the rate. These are very different statements. Media and politicians sometimes confuse or deliberately choose one vs. the other based on which sounds better. Always clarify what type of change is being described — absolute (percentage points) or relative (percent change).
How do I add or subtract a percentage from a number? +
To add a percentage: multiply by (1 + decimal). Example: $200 + 15% = $200 × 1.15 = $230. To subtract: multiply by (1 − decimal). Example: $200 − 20% = $200 × 0.80 = $160. This is faster than calculating the percent separately and then adding. For tax-inclusive pricing: to find the pre-tax price from a tax-included total, divide by (1 + tax rate). Example: $92.40 with 8% tax ― pre-tax = $92.40 ÷ 1.08 = $85.56.
What does “percent of” vs. “percent off” mean? +
These are commonly confused in retail. “20% OF $100” = $20 (you're computing 20%). “20% OFF $100” = $80 final price (you're subtracting 20%). “Pay only 80%” and “20% off” are the same thing. “Save 20%” means you pay 80% of the original price. Confusing these can lead to significantly misjudging deal values. When in doubt, compute the final dollar amount to make the most accurate comparison.