Free Online Tool
Percentage Calculator
Calculate any percentage instantly — find a percentage of a number, calculate percentage change, increase, decrease, or convert a ratio to a percent. No sign-up required.
A percentage calculator is a mathematical tool that evaluates the three core relationships in percentage arithmetic: finding what percentage one number is of another, calculating a percentage of a given value, and computing the percentage change between two values. Percentages — ratios expressed as fractions of 100 — underpin daily decisions in finance, retail, health, and data analysis, from calculating a sales discount or investment return to interpreting exam scores, tax rates, and population growth statistics.
Percentage Calculator – Complete Guide, Formulas & Examples
A percentage calculator helps you calculate percentages, percentage increases, percentage decreases, discounts, ratios, and percentage changes instantly. Percentages are used in business, finance, education, statistics, marketing, investments, taxes, and everyday shopping decisions.
Whether you need to calculate exam scores, salary increases, retail discounts, profit margins, tax rates, or business growth, this free percentage calculator provides fast and accurate results.
What Is a Percentage?
A percentage is a number expressed as a fraction of 100. The symbol (%) means "per hundred." Percentages make it easier to compare values and understand proportions.
Examples:
| Percentage | Meaning |
|---|---|
| 25% | 25 out of 100 |
| 50% | Half of a whole |
| 100% | The complete amount |
Percentage Formula
The standard percentage formula is:
| Formula Type | Formula |
|---|---|
| Basic Percentage | (Part ÷ Whole) × 100 |
| Percentage Increase | ((New − Old) ÷ Old) × 100 |
| Percentage Decrease | ((Old − New) ÷ Old) × 100 |
| Discount Calculation | Original Price × (Discount % ÷ 100) |
How to Calculate Percentage
To calculate a percentage:
- Identify the part value.
- Identify the whole value.
- Divide the part by the whole.
- Multiply the result by 100.
Example: If you scored 45 marks out of 60:
(45 ÷ 60) × 100 = 75%
Percentage Calculator Examples
| Calculation | Result |
|---|---|
| 20% of 500 | 100 |
| 15% of 200 | 30 |
| Increase from 100 to 120 | 20% |
| Decrease from 100 to 80 | 20% |
| 45 out of 60 | 75% |
| 3:4 ratio | 75% |
Percentage Increase Calculator
A percentage increase calculator measures growth between two values. It is commonly used for salary raises, revenue growth, investment performance, population growth, and business reporting.
Example:
If revenue increases from $10,000 to $12,000:
((12,000 − 10,000) ÷ 10,000) × 100 = 20%
Discount Calculator Guide
Discount calculations help determine savings and final sale prices during promotions, coupons, and retail sales.
Example:
A $200 item with a 25% discount:
- Discount Amount = $50
- Final Price = $150
Where Are Percentages Used?
Common Percentage Problems
- What is 20% of 500?
- What percent is 45 out of 60?
- How much is a 25% discount on $200?
- What is the percentage increase from 80 to 100?
- How do you convert a ratio such as 3:4 into a percentage?
Frequently Asked Questions
Divide the part by the whole, then multiply by 100. For example: 15 is what percent of 60? Calculate 15 ÷ 60 = 0.25, then 0.25 × 100 = 25%. Use the "What % Is X of Y" tab above to do this instantly.
Use the formula: ((New − Old) ÷ Old) × 100. For example, if a salary went from $50,000 to $55,000: ((55,000 − 50,000) ÷ 50,000) × 100 = 10% increase. Use the "% Change" tab above for automatic calculation.
Multiply the number by the percentage divided by 100. Example: 20% of 150 = 150 × (20 ÷ 100) = 150 × 0.2 = 30. Or use the "% of Number" tab at the top of this page for instant results.
Both use the same formula but produce opposite signs. A percentage increase occurs when the new value is higher than the original, yielding a positive result. A percentage decrease occurs when the new value is lower, yielding a negative result. For example, 100 → 75 is a −25% change (25% decrease).
Divide the first number by the second, then multiply by 100. Example: 3:4 → 3 ÷ 4 = 0.75 × 100 = 75%. Fractions work the same way: 7/8 = 7 ÷ 8 = 0.875 × 100 = 87.5%.
NexAlc's percentage calculator uses standard floating-point arithmetic and rounds results to 4 decimal places for precision. For financial calculations involving currency, results are rounded to 2 decimal places. All calculations run locally in your browser — nothing is sent to a server.
Methodology & Accuracy
All calculations use standard mathematical formulas as defined in international mathematics curricula and financial standards. Percentage of a number follows the formula P/100 × N; percentage change uses ((New − Old) / Old) × 100 per standard statistical practice. Results are computed in JavaScript's 64-bit IEEE 754 floating-point arithmetic and rounded to 4 significant decimal places to minimise floating-point drift.
For formal mathematical definitions, refer to: Khan Academy — Percent Introduction · MathIsFun — Percentage.
Last reviewed: .