How to Calculate Cumulative Percentage for a Pareto Analysis in Excel

Find the "vital few" causes behind most of your problems with a cumulative percentage column — the core of the 80/20 rule.

You will learn to

• Calculate a cumulative percentage on a sorted list
• Count the categories that make up 80% of the total
• Calculate cumulative % on an unsorted list

How it works

A Pareto analysis sorts causes from largest to smallest and adds a cumulative percentage column: =SUM($B$2:B2)/SUM($B$2:$B$8), filled down. The column climbs to 100%, and the rows up to roughly 80% are the "vital few" — the handful of causes worth fixing first.

To count how many causes it takes to reach 80%, use =COUNTIF(C2:C8,"<0.8")+1. If your list is not sorted, you can still get each item’s cumulative % with SUMIF: add every count greater than or equal to this one, then divide by the total.

=SUM($B$2:B4)/SUM($B$2:$B$8)