How to calculate cumulative percentage in Excel

Q: How do I find the categories that make up 80%?

Flag them with =C2<=80%, or include the one that crosses 80% with =C2-B2/SUM($B$2:$B$8)<80%.

Q: How do I make a Pareto chart?

Select the categories and counts and insert a Pareto chart (Insert, Statistic chart), or combine a column chart with the cumulative % on a secondary axis.

Q: Which category takes the total past 80%?

=XLOOKUP(0.8,C2:C8,A2:A8,,1) returns the first category whose cumulative percentage is at or above 80%.

Formula (Excel and Google Sheets)

=SUM($B$2:B2)/SUM($B$2:$B$8)

Divide a running total by the grand total: =SUM($B$2:B2)/SUM($B$2:$B$8), filled down.

Result on the example: one result per row in C2, filled down to C8
Works in: Every current version
Google Sheets: Same formula

See it work

The formula is already in C2, filled down to C8. Change any input and the result updates, or edit the formula to experiment.

How it works

SUM($B$2:B2) is a running total: its start is locked and its end moves down a row at a time. Dividing by the fully locked grand total, 400, turns it into a cumulative share that ends at 100%.

Sorted from the biggest category down, as here, this is a Pareto analysis: the top two defect types make up 60.75% of all defects.

=SUM($B$2:B2)/SUM($B$2:$B$8)

Result0.3625

$B$2:B2145
A range: one cell.
SUM($B$2:B2)145
SUM: Adds numbers and ranges. Skips text and blanks.
- number1$B$2:B2145
$B$2:$B$87 rows × 1 col: 145, 98, 61, 40, …
A range: 7 cells in one column.
SUM($B$2:$B$8)400
SUM: Adds numbers and ranges. Skips text and blanks.
- number1$B$2:$B$87 rows × 1 col: 145, 98, 61, 40, …
SUM($B$2:B2)/SUM($B$2:$B$8)0.3625
The / operator divides.

In Google Sheets

The same formula works in Google Sheets: =SUM($B$2:B2)/SUM($B$2:$B$8). We ran it in Google Sheets mode on the same data and it returns the same results.

Other ways to do it

Each one was run on the same example sheet.

Formula	Result	When to use it
=B2/SUM($B$2:$B$8)	36.3%, 24.5%, 15.3%…Different result	Each row's own share, not the running share. Shows each defect's share separately, such as 24.5% for dents.
=SUM(B$2:B2)/SUM(B$2:B$8)	36.3%, 60.8%, 76.0%…	Locking only the rows is enough when you fill down one column.

Common mistakes

Without sorting from largest to smallest first, the cumulative curve doesn't show which few categories matter most.
Locking both ends of the running total ($B$2:$B$2) or neither end breaks it. Lock only the start.
If the grand total isn't locked, it shrinks as you fill down and the percentages climb past 100%.

Try it yourself

Same data, empty answer cell. Your formula is graded instantly, then re-checked on changed data, so a typed-in number won't pass.

Calculate cumulative percentage

In C2, calculate the cumulative percentage of defects down to this row, then fill down to C8.

Questions

How do I find the categories that make up 80%?

Flag them with =C2<=80%, or include the one that crosses 80% with =C2-B2/SUM($B$2:$B$8)<80%.

How do I make a Pareto chart?

Select the categories and counts and insert a Pareto chart (Insert, Statistic chart), or combine a column chart with the cumulative % on a secondary axis.

Which category takes the total past 80%?

=XLOOKUP(0.8,C2:C8,A2:A8,,1) returns the first category whose cumulative percentage is at or above 80%.

Checked by running on 2026-10-30: every formula and result on this page was calculated by the Spreadsheet Practice formula engine, in both Excel and Google Sheets modes.