Math · Free Tool
Percentage Calculator
3 Ways to Calculate Percentages
Our free percentage calculator solves three common percentage problems instantly: finding a percentage of a number, figuring out what percentage one number is of another, and calculating percentage change between two values.
Last updated: May 10, 2026
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Percentage
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Percentage Calculator
3 Calculation Modes
Result
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Live Calculation
Calculation Summary
Enter values to see your percentage calculation update instantly.
Formula & Breakdown
Result
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Enter values
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Percentage Formulas Explained
Three essential formulas for every percentage calculation:
1
What is X% of Y?
Result
=
X
÷
100
×
Y
Example
20% of 500 = (20 ÷ 100) × 500 = 100
2
X is what percent of Y?
%
=
X
÷
Y
×
100
Example
75 is what % of 300? → (75 ÷ 300) × 100 = 25%
3
Percentage change from X to Y
% Change
=
×
100
Y − X
X
Example
From 80 to 100 → ((100−80) ÷ 80) × 100 = 25% increase
Common Percentage Calculations
- 15% of 200 = 30
- 25% of 80 = 20
- 8.5% sales tax on $120 = $10.20 (total $130.20)
- 7 is what % of 28? = 25%
- Raise from $50,000 to $55,000 = 10% increase
- Stock dropped from $200 to $160 = 20% decrease
Percentage Calculations by Use Case
The same formula applies across very different real-world scenarios. Here are common uses by category:
- GPA & grades — "I got 42 out of 50 on a test" → (42 ÷ 50) × 100 = 84%. Use Mode 2.
- Salary raise — "My salary goes from $62,000 to $67,000" → ((67,000 − 62,000) ÷ 62,000) × 100 = 8.06% raise. Use Mode 3.
- Sales tax — "8.25% tax on $95 purchase" → (8.25 ÷ 100) × 95 = $7.84 tax. Total = $102.84. Use Mode 1.
- Investment return — "Portfolio went from $12,000 to $14,400" → ((14,400 − 12,000) ÷ 12,000) × 100 = 20% return. Use Mode 3.
- Body weight change — "Lost 15 lbs from 200 lbs" → (15 ÷ 200) × 100 = 7.5% reduction. Use Mode 2.
Related Tools
- Discount Calculator — Uses percentage off to find final price and savings.
- Tip Calculator — Calculate percentage-based tips on restaurant bills.
- Salary Converter — Calculate percentage raises or salary comparisons.
- Unit Converter — Convert units that often involve percentages in formulas.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100. Formula: Result = (Percentage ÷ 100) × Number. Example: 30% of 250 = 0.30 × 250 = 75.
How do I calculate percentage increase or decrease?
Formula: % Change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result means increase; negative means decrease. Example: Price went from $40 to $50 = ((50−40) ÷ 40) × 100 = 25% increase.
What is 20% of 500?
20% of 500 = (20 ÷ 100) × 500 = 100. Quick mental math: move the decimal one place left for 10% ($50), then double it for 20% ($100).
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. Formula: % = (Part ÷ Whole) × 100. Example: 45 out of 180 total = (45 ÷ 180) × 100 = 25%.
How do I calculate sales tax?
Use Mode 1 (What is X% of Y?). Enter your tax rate as X and the pre-tax price as Y. The result is the tax amount. Add it to the original price for the total. Example: 8.25% tax on $150 = $12.38 tax → total $162.38.
How do I calculate a percentage raise in salary?
Use Mode 3 (Percentage Change). Enter your current salary as the "from" value and your new salary as the "to" value. Example: going from $58,000 to $63,000: ((63,000 − 58,000) ÷ 58,000) × 100 = 8.62% raise. You can also use Mode 1 to find what a specific percentage raise would equal in dollars.
What is 15% of 200?
15% of 200 = (15 ÷ 100) × 200 = 30. Quick mental check: 10% of 200 = 20, half of that is 10, so 15% = 20 + 10 = 30. This formula works for any "what is X% of Y?" question.
⚠️ Disclaimer: For informational purposes only. See our full Disclaimer.
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