Guide
Understand your Percentage result
A percentage calculator answers three common questions quickly: what a percentage of a number is, what percentage one number represents, and how much a value has changed.
Results are for general information. Review the site disclaimer before using a result for an important decision.
Identify the part and the whole
For a question such as 15% of 800, the percentage is 15 and the whole is 800. Divide 15 by 100, then multiply it by 800 to get 120.
For a question such as 120 is what percent of 800, divide the part by the whole and multiply by 100. The answer is 15%.
Use the original value for percentage change
Percentage increase or decrease compares the difference with the original value. If a price changes from 800 to 920, the difference is 120 and 120 divided by 800 is 15%.
Using the new value as the denominator gives a different answer, so check which number was there first before calculating the change.
Round after you calculate
Keep a few decimal places while working, then round the final answer to the level that makes sense for the task. Money is often rounded to two decimal places, while a quick estimate may only need a whole number.
For an invoice, exam, or formal report, check whether the instructions say how values should be rounded before using the result.