Percentage Calculator — Increase, Decrease & Ratio
Calculate percentage increase, decrease, ratio, and change rate. Find what percent one number is of another. All calculations run in your browser.
Features
- ✓Calculate X% of a number (e.g., 20% of 150)
- ✓Find what percent one number is of another
- ✓Calculate percentage increase between two numbers
- ✓Calculate percentage decrease between two numbers
- ✓Calculate percentage change (increase or decrease)
- ✓Instant calculation as you type
- ✓Clear formula display showing the calculation
- ✓Support for negative percentages
- ✓Perfect for discounts, taxes, and statistics
- ✓All calculations run locally in your browser
How to Use
- 1Select the calculation type you need.
- 2Enter the first value (percentage or number).
- 3Enter the second value (number or percentage).
- 4View instant results with the formula.
- 5Switch between different calculation types as needed.
- 6Use 'Percentage of a Number' for calculating discounts or tips.
- 7Use 'Percentage Increase/Decrease' for analyzing price or salary changes.
- 8Use 'Percentage Change' for comparing before-and-after values in reports.
Frequently Asked Questions
How do I calculate X% of a number?
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Multiply the number by the percentage divided by 100. For example, 20% of 150 = 150 × (20/100) = 150 × 0.2 = 30. This is useful for calculating discounts, taxes, or tips.
How do I find what percent one number is of another?
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Divide the first number by the second, then multiply by 100. For example, to find what percent 30 is of 150: (30 / 150) × 100 = 20%. This shows that 30 is 20% of 150.
What's the difference between percentage increase and decrease?
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Percentage increase measures how much a value grew: ((new - old) / old) × 100. Percentage decrease measures how much it shrunk: ((old - new) / old) × 100. Both use the original value as the base.
How do I calculate percentage change?
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Use the formula: ((new value - old value) / old value) × 100. A positive result indicates an increase, negative indicates a decrease. For example, from 80 to 100: ((100-80)/80) × 100 = 25% increase.
Can percentages be greater than 100%?
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Yes. Percentages over 100% mean the value is more than the whole. For example, if you had $100 and now have $250, that's a 150% increase. The new value is 250% of the original.
Is my calculation data sent to a server?
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No. All calculations happen entirely in your browser using JavaScript. Your numbers and results are never transmitted over the network. The tool works offline after the page loads.
How do I calculate a 20% tip on a restaurant bill?
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Use the 'Percentage of a Number' mode. Enter 20 as the percentage and the bill amount as the number. For example, a $50 bill × 20% = $10 tip. Total = $60. Alternatively, you can calculate 10% ($5) and double it for the same result.
How do I calculate percentage profit or loss?
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Use 'Percentage Change' mode. For profit: ((selling price - cost price) / cost price) × 100. For example, bought at $80, sold at $100: ((100-80)/80) × 100 = 25% profit. If selling at $60: ((60-80)/80) × 100 = -25% loss.
What is a percentage point vs percent?
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A percentage point is the arithmetic difference between two percentages. For example, if interest rates rise from 5% to 7%, that's a 2 percentage point increase but a 40% increase (7%-5% = 2 pp; (7-5)/5 = 40%). This distinction matters in finance, economics, and data reporting.
How do I calculate sales tax percentage?
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Use 'Percentage of a Number' mode. Enter the tax rate as the percentage and the pre-tax amount as the number. For example, 8.5% of $50 = $4.25 tax. The total is $54.25. For reverse calculation (extracting tax from total), use the formula: (total / (1 + rate)) × rate.
How do I calculate percentage for statistical data?
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Use 'Percentage Change' for comparing survey results year-over-year. Use 'Percentage Ratio' to find what proportion one subgroup represents. For example, if 45 out of 200 respondents chose option A: (45/200) × 100 = 22.5%. This is useful for market research, polls, and data analysis.
What does a 100% increase actually mean?
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A 100% increase means the value has doubled. If something goes from 50 to 100, that's a 100% increase because it increased by 50 (which is 100% of the original 50). A 200% increase means tripling (increase of 100 on top of 50 = 300% of original). This calculator helps avoid confusion between these common scenarios.
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