Percentage Calculator – Find % of a Number, Change & More
About the Percentage Calculator
The Percentage Calculator handles five common percentage problems in one tool: finding a percentage of a number, figuring out what percent X is of Y, solving for the base number when you know a percentage, calculating percentage increase or decrease between two values, and finding the percentage difference between two numbers.
It’s built for students, shoppers calculating discounts, and anyone working with percentages in budgets, grades, or business reports. Once you’ve solved your percentage problem, the Aspect Ratio Calculator and Pixel Calculator are useful for other quick math conversions you might need next.
The BigToolSite Team tested every tab with positive numbers, negative numbers, and edge cases like zero values to confirm each formula returns accurate results and clear labeling for increases versus decreases.
How to Use the Percentage Calculator
- Choose a tab: Basic, X is what % of Y?, X is Y% of what?, Percentage Change, or Percentage Difference.
- Enter your numbers into the fields for that calculation type.
- Click Calculate to see your result instantly.
- Use Clear to reset the fields and try a new calculation.
Example Usage
Basic: 20% of 150 = 30
X is what % of Y?: 45 is what % of 180? → 25%
Percentage Change: From 50 to 65 → +30% (Percentage Increase)
Percentage Difference: Value 1: 40, Value 2: 60 → 40% difference
Frequently Asked Questions
Percentage change measures growth or decline from a starting value to an ending value (useful for tracking increases or decreases over time), while percentage difference compares two values against their average without treating either one as the “starting” point.
Use the Basic tab, enter the discount percentage and the original price, and the result shows the discount amount — subtract that from the original price to get the final sale price.
Yes, the Percentage Change tab correctly labels results as an increase or decrease even when starting or ending values are negative, as long as the starting value isn’t zero.
Yes, your inputs and results are saved locally in your browser so they’re still there if you refresh the page, but they aren’t sent anywhere or shared.
Yes, it’s completely free with no signup required.
