Percentage Calculator
Calculate X% of Y, what percent X is of Y, or percent increase/decrease. Free to use, no signup required for occasional use.
What is the Percentage Calculator?
The Percentage Calculator is a free online tool that covers the three most common percentage calculations people need in everyday life, work, and school, all in one place. The first mode, 'X% of Y', answers questions like 'what is 15% of 80?' — useful for calculating tips, discounts, sales tax, or a portion of a total. The second mode, 'X is what percent of Y', answers questions like 'what percent of 200 is 45?' — useful for figuring out what share or proportion one number represents of another, such as a test score out of total points or a budget category as a share of total spending. The third mode, percentage increase or decrease, compares an original value to a new value and tells you the percentage change between them — useful for tracking price changes, salary raises, weight changes, business growth, or any before-and-after comparison. Doing these calculations by hand is simple in principle but easy to get backwards, especially the increase/decrease formula, which uses the original value as the base rather than the new value. This tool removes that ambiguity by clearly labeling each input and showing the calculation in plain language alongside the numeric result.
How to use it
First, choose the calculation mode that matches what you're trying to figure out: 'X% of Y' if you know a percentage and a total and want the resulting amount; 'X is what % of Y' if you know two amounts and want to know the percentage relationship between them; or '% increase / decrease' if you're comparing an original value to a new value. Enter the two required numbers into the labeled input fields — the labels update automatically based on the mode you've selected, so you always know which number goes where. Click 'Calculate' and the tool will display the result along with a plain-language explanation of what was calculated, such as '15% of 80 is 12' or 'that's a 25% increase from 80 to 100'. If you need to run a different calculation, just switch modes or update the numbers and click calculate again — there's no need to reload the page or start over.
Frequently asked questions
Which mode do I use to calculate a discount or tip?
Use 'X% of Y' — enter the discount or tip percentage as X and the original price as Y to get the discount or tip amount.
How does the percentage increase/decrease calculation work?
It compares your original value to your new value and expresses the difference as a percentage of the original value, showing whether it's an increase or a decrease.
Can the result be a negative percentage?
Yes, in the increase/decrease mode a negative result indicates a decrease from the original value to the new value.
Does this tool round the result?
Results are shown rounded to two decimal places for readability, based on the exact values you entered.