Percentage Calculator
Answer the four most common percentage questions in one place: what a percentage of a number is, what percent one number is of another, the percent change between two numbers, and how much a percent-off discount saves.
Each answer updates as you type, with the formula spelled out below, so you can check the math or use it on paper next time.
Calculator
What is X% of Y?
15% of 80 is 12
X is what percent of Y?
30 is 25% of 120
Percent change from X to Y
From 50 to 65 is a 30% increase
Percent off (discount)
25% off $120 saves $30 — you pay $90
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Calculation Formulas
Example:
15% of 80 = 12.
Example:
30 of 120 = 25%.
Positive is an increase, negative a decrease.
Example:
50 → 65 = +30%.
Example:
25% off $120 = $90.
Key Figures
| Figure | Value | Description |
|---|---|---|
| Rounding | 2 decimal places | Displayed results are rounded. |
Note: Results are estimates for planning purposes. Rates, fees, taxes, and insurance vary by lender and location — confirm exact figures with a licensed professional before making financial decisions.
Standards & Sources
Last verified: October 2026
- Standard arithmetic
The percentage formulas taught in school, applied exactly.
- Stacked discounts
Successive discounts multiply rather than add.
How to Use This Calculator
- Pick the question you want to answer.
- Enter the two numbers.
- Read the answer, which updates as you type.
- Use the formulas below to check or repeat the calculation.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 80 is 80 × 15 ÷ 100 = 12.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 is 30 ÷ 120 × 100 = 25% of 120.
How do I calculate percent change?
Subtract the old value from the new value, divide by the old value, and multiply by 100. Going from 50 to 65 is (65 − 50) ÷ 50 × 100 = a 30% increase.
How do I calculate a discount?
Multiply the price by the discount percentage ÷ 100 to get the savings, then subtract. 25% off $120 saves $30, so you pay $90. Two discounts stack on the reduced price: 25% then 10% off is 32.5% off, not 35%.
Guides to go with this calculator
How to Calculate a Percentage (4 Formulas)
Almost every percentage question is one of four formulas. Here they are with worked examples — plus the mental-math tricks for tips and sale prices, and the one mistake that trips up percent change.
How Much to Tip: A Guide for Every Situation
Tipping norms have drifted, and the screen at the counter doesn’t help. Here are the common U.S. ranges for every situation, whether to tip on tax, and the mental math to get it right in seconds.
Markup vs. Margin: Formulas and Conversion Table
A 50% markup is only a 33% margin. Mixing the two up is one of the most common pricing mistakes — here are both formulas, a conversion table, and how to set a price that hits your target.
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