Percentage Calculator
Free online percentage calculator. Three modes: what is X% of Y, X is what % of Y, and % change from X to Y. Live calculation, 100% browser-based, no signup.
Three Modes
Calculate % of a number, what percent one number is of another, and percent change (increase or decrease) between two values.
Live Calculation
Results update instantly as you type. No buttons to press, no waiting — just type the numbers and read the answer.
100% Private
All math runs in your browser. No data is uploaded, no signup, no cookies stored. Your numbers never leave your device.
Change Direction
The % change mode tells you both the magnitude and direction (increase or decrease), and handles negative and zero starting values gracefully.
How do I calculate what is X% of Y?
Use the first tab. Enter X in the "Percentage" field and Y in the "of number" field. The tool computes (X / 100) × Y. For example, 15% of 200 = 30.
How do I calculate what percent X is of Y?
Use the second tab. Enter X (the part) and Y (the whole). The tool computes (X / Y) × 100. For example, 30 is 15% of 200.
How is percent change calculated?
Use the third tab. Enter the original value and the new value. The formula is ((new − original) / |original|) × 100. A positive result is an increase, a negative result is a decrease.
Why does the tool show "—" sometimes?
A dash appears when the calculation is undefined — for example dividing by zero, or when one of the inputs is empty or not a valid number. Type both values to see the result.
Are the calculations rounded?
Results are rounded to at most 4 decimal places (trailing zeros stripped) for readability. The underlying math is full-precision floating point, so chained calculations stay accurate.
Ready to use the Percentage Calculator?
Free, no signup, no watermark. 100% browser-based. Your data never leaves your device.
Open the tool