Percentage Calculator
Calculate percentages instantly with three different calculation modes. Free, fast, and works offline.
How to Use the Percentage Calculator
This calculator offers three modes to cover every percentage calculation you might need:
- What is X% of Y? — Enter a percentage and a number to find the result. Example: What is 15% of 300? Answer: 45.
- X is what % of Y? — Enter two numbers to find what percentage the first is of the second. Example: 30 is what % of 120? Answer: 25%.
- Percentage Change — Enter an original value and a new value to find the percentage increase or decrease. Example: From 80 to 100 = 25% increase.
About Percentages
A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin per centum, meaning "by the hundred." Percentages are used everywhere in daily life — from calculating discounts and tips to understanding interest rates, tax, and statistics.
The basic percentage formula is: Result = (Percentage × Number) ÷ 100. For percentage change, the formula is: ((New - Old) ÷ Old) × 100. These formulas are the foundation of financial calculations, scientific analysis, and everyday math.
Worked Examples
Here are step-by-step solutions to common percentage problems people search for every day:
- What is 15% of 200? Multiply 200 by 15, then divide by 100. 200 × 15 = 3,000. 3,000 ÷ 100 = 30. So 15% of 200 is 30.
- What is 20% of 85? Multiply 85 by 20, then divide by 100. 85 × 20 = 1,700. 1,700 ÷ 100 = 17. So 20% of 85 is 17. This is useful for calculating a 20% tip on an $85 dinner bill.
- 45 is what percent of 180? Divide 45 by 180, then multiply by 100. 45 ÷ 180 = 0.25. 0.25 × 100 = 25%. So 45 is 25% of 180.
- What is the percentage change from 250 to 300? Subtract the old value from the new: 300 - 250 = 50. Divide by the old value: 50 ÷ 250 = 0.2. Multiply by 100: 0.2 × 100 = 20% increase.
- What is 7.5% of 1,200? Multiply 1,200 by 7.5, then divide by 100. 1,200 × 7.5 = 9,000. 9,000 ÷ 100 = 90. This is a common calculation for sales tax — 7.5% tax on a $1,200 purchase equals $90.
- What is the percentage decrease from 500 to 375? Subtract the new from the old: 500 - 375 = 125. Divide by the old: 125 ÷ 500 = 0.25. Multiply by 100: 0.25 × 100 = 25% decrease.
Quick Reference: Common Percentages
This table shows commonly needed percentage calculations at a glance. Use it as a quick reference for everyday math.
| Percentage | As Decimal | As Fraction | Of 100 | Of 250 |
|---|---|---|---|---|
| 5% | 0.05 | 1/20 | 5 | 12.50 |
| 10% | 0.10 | 1/10 | 10 | 25 |
| 15% | 0.15 | 3/20 | 15 | 37.50 |
| 20% | 0.20 | 1/5 | 20 | 50 |
| 25% | 0.25 | 1/4 | 25 | 62.50 |
| 33.3% | 0.333 | 1/3 | 33.33 | 83.33 |
| 50% | 0.50 | 1/2 | 50 | 125 |
| 75% | 0.75 | 3/4 | 75 | 187.50 |
Frequently Asked Questions
Multiply the number by the percentage and divide by 100. For example, 25% of 200 = (200 × 25) / 100 = 50. You can also move the decimal point two places left: 25% becomes 0.25, then 0.25 × 200 = 50.
Use the formula: ((New Value - Old Value) / Old Value) × 100. A positive result means an increase, and a negative result means a decrease. For example, going from 80 to 100: ((100 - 80) / 80) × 100 = 25% increase.
To find what percentage X is of Y, divide X by Y and multiply by 100: (X / Y) × 100. For example, 30 is what percent of 150? (30 / 150) × 100 = 20%.
Yes, this calculator uses standard mathematical formulas and provides results with up to 4 decimal places. It is suitable for general financial calculations. For professional accounting or tax purposes, always verify with a qualified professional.
If you know the result and the percentage, divide the result by the percentage and multiply by 100. For example, if 20% of a number is 50, the original number is 50 ÷ 20 × 100 = 250. This is useful when you know the discount amount and want to find the original price.
Simply move the decimal point one place to the left. For example, 10% of 450 is 45, and 10% of 82.50 is 8.25. You can use this shortcut to quickly estimate other percentages: 5% is half of 10%, 20% is double 10%, and 15% is 10% plus half of 10%.
A percentage point is an absolute difference between two percentages, while percent describes a relative change. For example, if an interest rate moves from 5% to 8%, it increased by 3 percentage points. But in relative terms, it increased by 60% (3 ÷ 5 × 100). This distinction is important in finance and statistics.
Divide the numerator by the denominator and multiply by 100. For example, 3/8 as a percentage: 3 ÷ 8 = 0.375, then 0.375 × 100 = 37.5%. Common fractions: 1/4 = 25%, 1/3 = 33.33%, 1/2 = 50%, 2/3 = 66.67%, 3/4 = 75%.