Percentage Calculator
Six ways to calculate percentages — find a percentage, percentage change, what percent one number is of another, and more. Every result comes with step-by-step working.
e.g. What is 15% of 200? → 30
e.g. 30 is what % of 200? → 15%
e.g. From 80 to 100 = +25% increase
e.g. 200 increased by 15% = 230
e.g. 30 is 15% of what number? → 200
Calculate tip amount and split between people
How to Calculate Percentages — All 6 Types
Percentages are one of the most universally useful concepts in everyday math — from shopping discounts to test scores, tax rates, tip amounts, and investment returns. A percentage is simply a way to express a number as a fraction of 100. The word comes from the Latin per centum, meaning "by the hundred." This calculator handles every common percentage scenario with step-by-step working. For discount-specific calculations, also see our Percent Off Calculator.
The 6 Core Percentage Formulas
1. What is X% of Y? → Result = Y × (X / 100)
2. X is what % of Y? → Result = (X / Y) × 100
3. % Change from A to B? → Result = ((B − A) / |A|) × 100
4. Y increased/decreased by X% → New = Y × (1 ± X/100)
5. X is Y% of what? → Whole = X / (Y / 100) = X × 100 / Y
6. Tip: Bill × (Tip% / 100) → Total = Bill + Tip; Per person = Total / n
All six modes above calculate instantly as you type, with step-by-step working shown.
Mental Math Tricks for Common Percentages
10% — Move the decimal point one place left. 10% of $85 = $8.50. 5% — Find 10% then halve it. 5% of $85 = $4.25. 20% — Find 10% and double it. 25% — Divide by 4. 25% of $80 = $20. 50% — Divide by 2. 1% — Move the decimal two places left. 15% — Find 10% + 5%. These tricks are especially useful when calculating tips at restaurants or estimating discount savings while shopping.
Percentage Change vs Percentage Points
One of the most common percentage mistakes is confusing percentage change with percentage points. If an interest rate goes from 2% to 3%, it has increased by 1 percentage point — but it has increased by 50% (because 3 is 50% more than 2). Politicians and media often blur this distinction. Example: "The unemployment rate fell from 8% to 6%" — this is a fall of 2 percentage points, but a 25% decrease in the unemployment rate. Always ask: "percent of what?" Use Mode 3 above to calculate the true percentage change between any two values. For grade-related percentage calculations, try our Grade Calculator.
Frequently Asked Questions
Common questions about percentage calculations, formulas, and how to use this calculator
Percentage = (Part / Whole) × 100. Example: What percentage is 45 of 180? (45 / 180) × 100 = 25%. Use Mode 2 above — enter 45 in the first box and 180 in the second. Common uses: test scores (you got 36 out of 45 — what %?), tracking progress (completed 8 of 20 tasks — what %?), market share (your company sold 500 of 2,000 total units — what share?). For grade-based percentage calculations, also try our Grade Calculator.
% Change = ((New Value − Old Value) / |Old Value|) × 100. If the result is positive, it's an increase; negative means a decrease. Example 1 (increase): Price went from $80 to $100 → ((100 − 80) / 80) × 100 = 25% increase. Example 2 (decrease): Revenue fell from $500 to $400 → ((400 − 500) / 500) × 100 = −20% decrease. Use Mode 3 above to calculate this instantly. Note: percentage change is always relative to the original value, not the new one. A common mistake is dividing by the new value instead. For investment return calculations, see our Average Calculator.
Result = Number × (Percentage / 100). Or equivalently, move the decimal two places left and multiply. Examples: 15% of 200 = 200 × 0.15 = 30. 7% of $1,250 = 1250 × 0.07 = $87.50. 0.5% of 10,000 = 10,000 × 0.005 = 50. Use Mode 1 above for instant calculations. Practical uses include calculating sales tax (e.g. 8% of $45.99), tips (18% of a restaurant bill), discounts (see our Percent Off Calculator), and interest rates.
Whole = Part × (100 / Percentage) = Part / (Percentage / 100). Example: You paid $24 in tax, which is 8% of the original price. What was the original price? $24 / 0.08 = $300. Or: You scored 72 on a test and got 90% — what was the total possible score? 72 / 0.90 = 80 points. Use Mode 5 above. This calculation is also useful for finding a pre-discount original price from a sale price — though for that specific case, our Percent Off Calculator (Reverse mode) is more convenient.
((−30 − (−50)) / |−50|) × 100 = (20/50) × 100 = 40% improvement. The key is dividing by the absolute value of the original to get a meaningful percentage. For percentage of a negative number: 20% of −$150 = −$30 (same formula, same logic). Our Mode 3 (Percentage Change) uses the absolute value of the starting number for the correct result.