When to use each type
To calculate a discount or price increase, use "increase/decrease a number by percent." To compare sales or performance between two periods (like two consecutive months), use "percent change between two numbers." "What is X% of a number" and "what % is one number of another" are inverse operations of each other, covering the most common everyday percentage uses.
Note: when using "percent change," a negative sign appears when the value has decreased, and positive when it has increased — the calculator also clarifies this with the word "increase" or "decrease" next to the number to avoid any confusion.
FAQ
What's the difference between "percent change" and "increase/decrease by percent"?
"Percent change" takes two values (before and after) and gives you the percentage of the difference between them. "Increase/decrease by percent" is the reverse operation: you enter a value and a percentage, and get the new value directly after applying it.
How do I calculate a discount percentage on a product's price?
Choose "increase/decrease a number by percent" mode, enter the original price and the discount percentage, and select "decrease" to get the final price directly along with the amount saved.
Can I enter decimal or negative numbers?
Yes, all modes accept decimals, and some accept negative values (like percent change mode), as long as the base number isn't zero to avoid dividing by zero.
Source
Standard mathematical formulas for percentage calculations.
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Last updated: July 2026
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