Percent of a number
To find X% of Y, divide the percent by 100 and multiply by the number. Example: 20% of 150 is 0.20 x 150 = 30.
What percent is one number of another?
Divide the part by the whole, then multiply by 100. Example: 12 out of 60 is 12 / 60 x 100 = 20%.
Percentage change
Percentage change compares the change to the original value: (new value - old value) / old value x 100. If the original value is zero, percentage change is undefined.
Common mistakes
Do not confuse percentage points with percent change. Moving from 10% to 15% is a 5 percentage-point increase, but a 50% relative increase.
Use the calculator
Open the Percentage Calculator to calculate these modes with validation and examples.
Last reviewed: 2026-05-13