Percentage Calculator
Master percentage calculations with 6 advanced modes. Calculate percentages, markups, discounts, interest, and more—all in one powerful tool.
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What is a Percentage Calculator?
A percentage calculator is a digital tool that instantly solves percentage-based math problems without manual calculation. It's used to find what percentage one number is of another, calculate percentage increases or decreases, apply discounts, calculate markups, compute compound interest, and much more. Whether you're shopping, managing finances, analyzing data, or doing homework, a percentage calculator eliminates errors and saves time.
Our advanced percentage calculator supports 6 different calculation modes, allowing you to solve virtually any percentage problem you encounter. It's free, private (works offline), and requires no registration or technical knowledge.
Six Advanced Calculation Modes
Percentage Value
Calculate what percentage of a total amount. Perfect for taxes (What is 8% tax on $500?), tips (What is 18% gratuity?), and commissions.
Formula: (X ÷ 100) × YPercentage of Total
Find what percentage one number is of another. Great for test scores (85 out of 100 = 85%), body fat, market share, and proportions.
Formula: (X ÷ Y) × 100Percentage Change
Calculate increase or decrease between two values. Essential for price changes, salary increases, weight loss, and investment returns.
Formula: ((New - Old) ÷ Old) × 100Markup Calculator
Convert cost price to selling price by adding a markup percentage. Vital for retail businesses, e-commerce, and pricing strategies.
Selling Price = Cost + (Cost × Markup%)Discount Calculator
Apply percentage discounts to original prices. Perfect for shopping sales, promotional pricing, wholesale calculations, and price negotiations.
Final Price = Original - (Original × Discount%)Compound Interest
Calculate interest earned over multiple time periods. Essential for savings accounts, investments, crypto, and financial planning.
Interest = Principal × (1 + Rate)^Time - PrincipalHow to Use the Percentage Calculator
- Select a Calculation Mode: Choose from 6 modes depending on what you want to calculate (percentage value, change, discount, etc.).
- Enter Your Values: Input the numbers in the provided fields. The calculator accepts whole numbers, decimals, and negative values.
- View Instant Results: The answer appears immediately as you type. No need to press a button or wait for processing.
- See the Formula: The calculator displays the exact formula used, so you understand the calculation and can verify manually if needed.
- Customize Display: Choose decimal places (0-5), toggle decimals on/off, and compare original vs. result values.
- Download or Copy: Copy results to clipboard or download as a text file for records and sharing.
- Track History: Calculations are saved in history (up to 10 recent calculations) for quick reference.
Real-World Use Cases for Percentage Calculators
Shopping & Retail
Calculate sale prices with discounts, compare percent-off deals, estimate final prices with tax, calculate cashback percentages, and evaluate bulk discounts.
Business & Finances
Calculate profit margins, analyze growth rates, determine markups for pricing, compute tax amounts, track revenue changes, and evaluate investment returns.
Health & Fitness
Track weight loss percentages, calculate body fat percentage, determine health goal progress, analyze fitness improvements, and monitor calorie burn percentages.
Education & Testing
Calculate test scores and grade percentages, analyze attendance rates, determine pass/fail percentages, track student progress, and evaluate assessment results.
Personal Finance
Calculate tips and gratuities, track savings goals, determine budget percentages, compute loan interest, analyze expense ratios, and plan financial objectives.
Data Analysis & Statistics
Calculate percentage changes in data, analyze statistical distributions, determine conversion rates, evaluate market share, and assess performance metrics.
Why Choose Our Percentage Calculator?
100% Free & Private
No registration, no hidden fees, no data collection. All calculations happen locally in your browser—completely secure and offline-capable.
Instant Calculations
Real-time results as you type. No loading screens, no waiting. Lightning-fast performance on any device.
6 Advanced Modes
Covers virtually every percentage scenario: values, totals, changes, markups, discounts, and compound interest.
Educational & Transparent
See formulas for every calculation, learn how percentages work, and verify results mathematically.
Download & Save Results
Export calculations as files, maintain calculation history, and share results with colleagues or clients.
Mobile-Friendly Design
Responsive interface works perfectly on desktop, tablet, and smartphone. Use anywhere, anytime.
Percentage Formulas Cheat Sheet
| Formula Name | Formula | Example |
|---|---|---|
| Percentage Value | (X ÷ 100) × Y | 20% of 150 = (20 ÷ 100) × 150 = 30 |
| Percentage of Total | (X ÷ Y) × 100 | 45 out of 100 = (45 ÷ 100) × 100 = 45% |
| Percentage Change | ((New - Old) ÷ Old) × 100 | 100 to 150 = ((150-100)÷100)×100 = 50% |
| Percentage Increase | Old + (Old × Increase%) | 100 + 20% = 100 + (100 × 0.20) = 120 |
| Percentage Decrease | Old - (Old × Decrease%) | 100 - 20% = 100 - (100 × 0.20) = 80 |
| Discount Price | Original - (Original × Discount%) | $100 - 25% = $100 - $25 = $75 |
| Markup Price | Cost + (Cost × Markup%) | $50 + 100% = $50 + $50 = $100 |
| Compound Interest | Principal × (1 + Rate)^Time | $1000 at 5% for 3 yrs = $1000 × 1.05³ = $1157.63 |
Common Percentage Calculation Mistakes to Avoid
- Confusing "% of" with "% change":
20% of 100 is 20. But if 100 increases BY 20%, it becomes 120. They're different calculations with different results.
- Reversing the numerator and denominator:
"5 out of 20" is (5 ÷ 20) × 100 = 25%, NOT (20 ÷ 5) × 100 = 400%. Always put the part on top.
- Forgetting to multiply by 100 (or divide percentage by 100):
When using 20%, use 0.20 in formulas, not 20. Using 20 directly will give 2000% of the correct answer.
- Stacking percentages additively instead of multiplicatively:
Two 50% discounts don't equal 100% off. They equal 75% off (50% off leaves 50%, then 50% off that leaves 25%, so 75% total discount).
- Using percentage increase/decrease backward:
A 50% increase followed by a 50% decrease does NOT return to the original. $100 → $150 → $75 (lost $25).
Tips for Percentage Calculations
- Use our calculator to verify manual calculations.
Build confidence in your math skills by comparing your answers with the tool's results.
- Always understand the context of the percentage.
Know if it's "% of", "% change", "% off", or "% increase"—each uses different formulas.
- Use the "Show Comparison" feature to double-check.
Compare original values with results to ensure your calculation makes sense logically.
- Download important calculations for records.
Keep documentation for business, taxes, or personal reference using the download feature.
- Adjust decimal places based on your use case.
Use 2 decimals for money, 0 for whole numbers, and more for scientific calculations.
Frequently Asked Questions
How do I calculate a percentage of a number?
To calculate X% of Y, use the formula: (X ÷ 100) × Y. For example, to find 20% of 150: (20 ÷ 100) × 150 = 0.2 × 150 = 30. This is useful for calculating tips, taxes, discounts, and commissions. Our calculator solves this instantly in the 'Percentage Value' mode.
How do I calculate what percentage one number is of another?
To find what percentage X is of Y, use: (X ÷ Y) × 100. For example, 25 is what % of 200? (25 ÷ 200) × 100 = 12.5%. This is commonly used for test scores (45 out of 100 = 45%), body fat percentages, or business metrics. Use the 'Percentage of Total' mode for quick calculations.
What is the formula for percentage increase or decrease?
Percentage Change = ((New Value - Old Value) ÷ Old Value) × 100. If positive, it's an increase; if negative, it's a decrease. Example: Price went from $100 to $150. Change = ((150 - 100) ÷ 100) × 100 = 50% increase. Use this to track salary increases, price changes, weight loss, or stock performance.
How do I calculate a discount price?
Final Price = Original Price × (1 - Discount%). Example: Item costs $100 with 20% off. Final = $100 × (1 - 0.20) = $100 × 0.80 = $80. Or use the formula: Final = Original - (Original × Discount%). Our Discount Calculator mode handles this instantly. Perfect for shopping, sales analysis, and promotional pricing.
How do I calculate markup and selling price?
Selling Price = Cost Price + (Cost Price × Markup%). Example: Item costs $50, you add 40% markup. Selling Price = $50 + ($50 × 0.40) = $50 + $20 = $70. This is essential for retail, e-commerce, wholesale businesses, and service providers. Use our Markup Calculator mode to instantly find retail prices.
What is compound interest and how is it calculated?
Compound Interest = Principal × (1 + Rate)^Time - Principal. Example: $1000 at 5% annual interest for 3 years = $1000 × (1.05)³ - $1000 = $1157.63 - $1000 = $157.63 interest earned. This applies to savings accounts, investments, loans, and cryptocurrency. The calculator shows interest earned after your specified time period.
Is this percentage calculator free and secure?
Yes! Our percentage calculator is 100% free with no hidden fees, registration, or data collection. All calculations happen locally in your browser—your data never reaches our servers. It's completely private and secure. You can use it offline after loading the page. No ads, no popups, just pure calculator functionality.
Can I download my calculation results?
Yes! After any calculation, click the 'Download Result' button to save a text file containing the formula, inputs, and result. This is useful for record-keeping, business documentation, or sharing with colleagues. The file includes a timestamp for reference. You can also copy results individually.
What decimal places should I use for my calculations?
It depends on your use case. For money/currency, use 2 decimal places. For percentages and general calculations, 2-3 places is standard. For scientific work, use 4-5 places. Our calculator lets you choose 0-5 decimal places. Toggle 'Show Decimals' off for whole numbers (useful for counting/inventory). Adjust this in the Display Options panel.
Why do I need a percentage calculator?
Percentage calculations are used constantly in daily life: calculating tips, taxes, discounts while shopping, tracking weight loss, analyzing test scores, understanding investment returns, pricing products, evaluating business growth, and more. Mental math is prone to errors, especially with percentages. This calculator ensures accuracy, saves time, and provides formulas so you understand the math. Having a reliable percentage calculator prevents costly mistakes in business and personal finance.
What are real-world applications of percentage calculations?
Retail: Apply discounts, calculate markups, find sale prices. Finance: Compute interest, loan payments, investment returns, tax calculations. Health: Track weight loss percentage, BMI calculations, medication dosages. Education: Calculate test scores, grade points, attendance rates. Business: Analyze profit margins, growth rates, market share, revenue changes. Personal: Tips calculation, budget percentages, savings goals. Our calculator handles all these scenarios with dedicated modes for common use cases.