Running Total in Excel: Cumulative Sum With One Formula
Create a running total in Excel with =SUM($B$2:B2) filled down, why the half-locked range works, and alternatives for tables, filters and Microsoft 365.
By Ayoub Farid · · 1 min read
A running total (cumulative sum) shows how a total builds up row by row: sales year to date, account balance, progress toward a goal. One formula does it, and it's a favourite in job tests because it needs a half-locked range.
The formula
Sales in B2:B13. In C2:
=SUM($B$2:B2)Fill down to C13. Row 3 becomes =SUM($B$2:B3), row 4 =SUM($B$2:B4)…
Why it works
$B$2is locked: the range always starts at the first month.B2is relative: the end moves down one row each time.
So the range grows. If you forget the $, every row sums just two cells: =SUM(B3:B3), wrong from row 3 onwards. That's the "Lock that cell" mistake. See absolute references.
Alternative: previous total plus this row
C2: =B2 C3: =C2+B3, filled down.
Simple, but if you delete a row you get #REF!.
Running balance (in and out)
Money in (B), money out (C). In D2:
=SUM($B$2:B2)-SUM($C$2:C2)Running total by category
Restart the total for each category in column A:
=SUMIF($A$2:A2,A2,$B$2:B2)Microsoft 365: one spilling formula
=SCAN(0,B2:B13,LAMBDA(a,b,a+b))Advanced, but neat: one formula, whole column.
Practise it
Running totals ("What are sales so far by each month?") are part of Cellio's fill-down lessons. If the copies point at the wrong cells, the feedback says your first row is right but the copies drift, and shows =SUM($B$2:B2).
Frequently asked questions
How do I make a cumulative sum in Excel?
In the first row write =SUM($B$2:B2) and fill down.
Why does my running total only add one cell?
The start of the range isn't locked. Use $B$2.
How do I do a running total in Google Sheets?
The same =SUM($B$2:B2) formula works.
Can a running total reset each month or category?
Yes, use =SUMIF($A$2:A2,A2,$B$2:B2) with the category in column A.