The working behind the answer
How to use this calculator
A percentage describes an amount out of one hundred. Choose the question that matches your task before entering your numbers. The base matters: 20 out of 80 is 25%, while 80 out of 20 is 400%. Values above 100% can be meaningful, so this calculator allows them.
The formula
Percentage of a number
Result = number × percentage ÷ 100
One number as a percentage
Percentage = part ÷ whole × 100
Find the original whole
Whole = part ÷ (percentage ÷ 100)
A worked example
15% of 240 is 36. Write 15% as 0.15, then multiply 240 × 0.15. To reverse the calculation, 36 ÷ 0.15 gives the original whole of 240.
Good to know
For an increase or decrease between an old and new value, use the percentage change calculator. A percentage of a number and a percentage change answer different questions.
Common questions
Can a percentage be more than 100?
Yes. For example, 150% of 20 is 30. It represents one and a half times the starting amount.
Why can’t the whole be zero?
A part-to-whole percentage divides by the whole. Division by zero does not produce a defined percentage.