Percentage Calculator
Three common percentage calculations in one place — updated live as you type.
What is X% of Y?
X is what percent of Y?
Percentage increase / decrease
How to Calculate a Percentage
- To find a percentage of a number, enter the percent and the base number in the "What is X% of Y?" section — the result updates as you type.
- To find what percent one number is of another, enter both numbers in the "X is what percent of Y?" section.
- To measure a percentage change, enter the starting ("From") and ending ("To") values in the third section.
- Read the result directly below each section — no button click needed, everything is live.
Frequently Asked Questions
What's the difference between the three calculators on this page?
The first finds a portion of a number (e.g., 20% of 150), the second finds what percentage one number represents of another (e.g., 30 is what % of 150), and the third finds the percent change between two values (e.g., going from 80 to 100).
Why does the percentage increase/decrease calculator use the absolute value of From?
The tool divides the change by the absolute value of the starting number so that a negative starting value doesn't flip the sign of the result — this keeps increase and decrease meaning what you'd expect even when your starting number is negative.
Why is my result blank?
Each calculator only shows a result once both required fields contain valid numbers; if you leave a field empty or the Y or From value is zero, the result box stays empty since that math is undefined.
How many decimal places does the calculator show?
Results are shown to up to 4 decimal places using locale-aware number formatting, so you get more precision than a typical whole-number percentage answer.
Can this tool calculate percentage change for a value that goes down?
Yes — if To is smaller than From, the tool automatically labels the result a decrease and shows the percentage drop, rather than a negative increase.