Percentage & Discount Calculator
Calculate percentages, percentage change, and sale discounts instantly. Find what a percentage of a number is, work out a price increase or decrease, or see exactly how much you'll save on a discounted item - free, no sign-up required.
All calculations happen instantly in your browser as you type.
How percentage calculations work
A percentage is simply a way of expressing a number as a fraction of 100. To find a percentage of a number, you convert the percentage to a decimal (divide by 100) and multiply it by the number. To find what percentage one number is of another, you divide the part by the whole and multiply by 100. These two operations cover most everyday percentage questions, from calculating a tip to figuring out a test score.
How percentage change and discounts are calculated
Percentage change measures how much a value has increased or decreased relative to its starting point, calculated as (new value - original value) / original value x 100. A positive result means an increase; a negative result means a decrease. A discount calculation uses a similar idea in reverse: it takes an original price, applies a percentage reduction, and shows both the final sale price and the exact dollar amount saved - useful for checking a store's advertised discount or comparing deals before you buy.
Common searches this calculator answers
- What is X% of Y?
- X is what percent of Y?
- Percentage increase or decrease calculator
- Discount calculator - how much will I save?
- Sale price calculator online free
- How to calculate a percentage change between two numbers
Related keywords and search terms
How to use this calculator
- Choose a mode at the top: "Percent Of" for basic percentage math, "% Change" for increase/decrease between two numbers, or "Discount" for sale price calculations.
- Enter your numbers into the fields - results update instantly as you type.
- For discounts, enter the original price and the discount percentage to see the final price and total savings.
Tips
- When comparing sale discounts, always check the final price, not just the advertised percentage off - a 40% discount on a marked-up price can be worse than a 20% discount on a fair price.
- For stacked discounts (like 20% off, then an extra 10% off), apply them one at a time rather than adding the percentages together - the true combined discount is usually smaller than adding the two numbers.
- A negative result in the "% Change" mode means the value decreased; a positive result means it increased.
- This calculator doesn't include sales tax - add tax to the final price separately if your total needs to reflect it.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For example, 20% of 150 is (20 / 100) x 150 = 30.
How do I find what percentage one number is of another?
Divide the part by the whole, then multiply by 100. For example, to find what percent 30 is of 150: (30 / 150) x 100 = 20%.
What's the formula for percentage increase or decrease?
Subtract the original value from the new value, divide that by the original value, then multiply by 100. A positive result is a percentage increase; a negative result is a percentage decrease.
Does stacking two discounts equal adding the percentages together?
No. Two discounts applied one after another (like 20% then 10%) result in a smaller total discount than simply adding them (30%), because the second discount applies to an already-reduced price, not the original price.
Does the discount calculator include sales tax?
No, this calculator shows the discounted price before tax. If your purchase includes sales tax, add it to the final price shown separately.
Is this calculator free to use?
Yes, completely free with no sign-up required, and you can recalculate as many times as you like.
