FormulaMath
Build a running total down a column
Fill one SUM formula down a column and have each row total everything above it, using an anchored starting cell instead of rewriting the range.
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Your formula
=SUM($B$2:B2)
Works in both Excel and Google Sheets unless the fine print below says otherwise.
Why it's built this way
- →The $ signs on start_cell lock both the column and row of that reference, so it never moves when the formula is filled down; current_cell has no $ signs, so it updates to match whatever row the formula lands on.
- →That mix — one end absolute, one end relative — is the entire trick: row 5's formula sums $B$2:B5, row 6's sums $B$2:B6, and each one automatically includes everything above it plus itself.
- →It's a single formula written once and filled down, rather than a different manually typed range on every row.
The fine print
- →Forgetting the $ signs on start_cell is the classic mistake: both ends of the range then shift together when filled down, so every row sums a fixed-size window instead of an expanding one — a running total that silently isn't.
- →Inserting or deleting a row above the anchored cell shifts what $B$2 points to, along with every formula built on it — worth a spot-check after any structural edit to the sheet.
- →Works identically in Excel and Google Sheets, $ anchoring included.