Percentage Calculator

Percentage Calculator - Free Online Percent Calculation Tool

Solve any percentage problem instantly with our free online Percentage Calculator. This all-in-one tool handles three of the most common percentage calculations on a single page: finding a percentage of a number, determining what percentage one number is of another, and calculating the percentage change between two values. Results update in real time as you type, so there is no need to click a button or wait for results.

Percentages come up constantly in everyday life, from calculating discounts while shopping to understanding financial growth, analyzing test scores, computing tips, and interpreting statistics. This calculator removes the mental math and gives you precise answers in an instant, whether you are dealing with simple or complex percentage problems.

How to Use

1. Mode 1 - What is Y% of X?: Enter the base number (X) and the percentage (Y). The result shows immediately. For example, enter 200 and 15 to find that 15% of 200 is 30.
2. Mode 2 - X is what % of Y?: Enter the part (X) and the whole (Y). The result tells you the percentage. For example, enter 45 and 200 to find that 45 is 22.5% of 200.
3. Mode 3 - Percentage Change: Enter the old value and the new value. The result shows both the percentage change and the absolute difference. For example, entering 80 and 100 shows a 25% increase with a difference of 20.
4. All three modes work independently and calculate in real time. Simply type your numbers and read the results.

Percentage Formulas

• Y% of X = X × (Y / 100). This is the most basic percentage calculation, used for discounts, tips, tax amounts, and proportional values.
• X is what % of Y = (X / Y) × 100. This formula determines the ratio of a part to a whole, expressed as a percentage. Used for test scores, completion rates, and market share calculations.
• Percentage Change = ((New Value - Old Value) / Old Value) × 100. A positive result indicates an increase, while a negative result indicates a decrease. Commonly used in financial analysis, sales tracking, and performance metrics.

Real-World Examples

• Shopping discounts: A $80 jacket is 25% off. Use Mode 1: 25% of 80 = $20 discount, so you pay $60.
• Test scores: You scored 42 out of 50. Use Mode 2: 42 is 84% of 50.
• Salary increase: Your salary went from $55,000 to $60,500. Use Mode 3: That is a 10% increase ($5,500 difference).
• Restaurant tip: The bill is $65 and you want to leave 18%. Use Mode 1: 18% of 65 = $11.70 tip.
• Investment returns: Your stock went from $150 to $135. Use Mode 3: That is a -10% decrease ($15 loss).

Frequently Asked Questions

Q. What is the difference between percent and percentage point?

A. Percent (%) is a ratio expressed out of 100, while a percentage point (%p) measures the absolute difference between two percentages. For example, if an interest rate rises from 3% to 5%, that is a 2 percentage point increase. However, in percentage terms, it is approximately a 66.7% increase (because 2 is 66.7% of 3). This distinction is important in finance, economics, and statistics, where confusing the two can lead to significant misunderstandings.

Q. How do I calculate a reverse percentage (find the original price before a discount)?

A. If you know the discounted price and the discount percentage, divide the discounted price by (1 - discount/100). For example, if an item costs $60 after a 25% discount, the original price is $60 / (1 - 0.25) = $60 / 0.75 = $80. You can verify this using Mode 1: 25% of $80 = $20, and $80 - $20 = $60.

Q. Why does the percentage change show a different magnitude for increases versus decreases?

A. Percentage change is calculated relative to the original (old) value. Going from 100 to 150 is a 50% increase, but going from 150 back to 100 is only a 33.3% decrease. This asymmetry occurs because the base value (denominator) changes. A 50% increase followed by a 33.3% decrease returns you to the starting point. This is a fundamental property of percentages that is important to understand when interpreting financial data and statistics.