Percentage Calculator
Every percentage formula you’ll ever need — percentage of a number, change, increase, decrease, difference, and reverse percentage — with instant step-by-step explanations.
Enter a percentage and a number to see the result.
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Enter original and new values to calculate percentage change.
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Enter the original value and increase percentage.
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Enter the original value and decrease percentage.
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Enter both numbers to find the percentage relationship.
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Enter two values to find the percentage difference between them.
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Enter the final value and the percentage that was applied.
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Enter the part and total to see what percentage the part represents.
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How to Calculate Percentages: Every Formula Explained
Percentages appear in almost every area of daily life — from calculating discounts and tax to understanding pay rises, exam scores, and investment returns. This guide covers all 8 types of percentage calculations with real-world examples and easy-to-follow formulas.
Finding X% of a Number
The most common percentage question. To find 20% of 500: divide 20 by 100 to get 0.2, then multiply by 500 to get 100. Used for: tips, discounts, commission, tax, and exam marks.
Percentage Change
Measures how much a value grew or shrank relative to its starting point. If a stock moved from $80 to $100: (100−80) ÷ 80 × 100 = +25%. Negative results mean a decrease. Used in finance, sales, and analytics.
Reverse Percentage
Work backwards to find the original value. If a product costs $85 after a 15% discount, the original price was 85 ÷ 0.85 = $100. Useful for VAT-exclusive prices, pre-discount values, and tip calculations.
Percentage Difference
Unlike percentage change, this is order-independent — comparing 90 and 110 gives the same result as comparing 110 and 90. Formula uses the average as the denominator: |90−110| ÷ 100 × 100 = 20%.
📐 Real-World Percentage Examples
All 8 Percentage Formulas at a Glance
| Calculation Type | Formula | Example |
|---|---|---|
| X% of Y | (X ÷ 100) × Y | 20% of 500 = 100 |
| % Change | ((New − Old) ÷ Old) × 100 | 80 to 100 = +25% |
| % Increase | Original × (1 + P ÷ 100) | 500 + 20% = 600 |
| % Decrease | Original × (1 − P ÷ 100) | 200 − 25% = 150 |
| X is what % of Y | (X ÷ Y) × 100 | 45 ÷ 180 × 100 = 25% |
| % Difference | |V1−V2| ÷ avg(V1,V2) × 100 | 90 vs 110 = 20% |
| Reverse % (decrease) | Final ÷ (1 − P ÷ 100) | 85 after −15% = 100 |
| % of Total | (Part ÷ Total) × 100 | 250 ÷ 1000 × 100 = 25% |
Percentage vs Percentage Points vs Percentile — Don’t Mix Them Up
Percentage — a share of a whole, measured out of 100. For example, 25% of 200 = 50. It tells you how large one part is compared with the total.
Percentage point — the absolute difference between two percentages. Going from 20% to 25% is a 5-percentage-point rise, but a 25% relative increase. Mixing these two up is the most common percentage mistake.
Percentile — a rank, not a score. Scoring in the 90th percentile means you outperformed 90% of the group. It is not the same as scoring 90%.
5 Everyday Percentage Calculations
Percentages show up everywhere — in payslips, shopping carts, and investment statements. Here are five calculations people use all the time.
- Salary hike: $50,000 → $55,000 = a 10% raise (5,000 ÷ 50,000 × 100).
- GST / VAT: a $200 item with 18% tax = $36 tax, $236 total.
- Investment return: $1,000 → $1,150 = a 15% return.
- Exam score: 45 out of 60 = 75%.
- Body-fat change: 25% → 20% body fat = 5 percentage points down, a 20% relative drop.