Google Sheets dropdown auto-fill formula builder
Pick from a dropdown, and the other cells fill in by themselves — that is one lookup formula per cell. The copy on every blog hard-codes somebody else's table, and the four questions under every tutorial (my values aren't in the first column · it shows #N/A until something is picked · it broke when I copied it down · which number goes in the middle) are each one changed piece. This page writes it against your table, and switches to XLOOKUP when VLOOKUP structurally can't do it.
Describe your table, then hit Build.
You'll get the formula, the steps to make the dropdown, and a table of exactly what it does — pick by pick:
=IFERROR(VLOOKUP(F2,A2:C9,2,FALSE),"")Nothing is sent anywhere but this page, and nothing is stored.
Why the tool sometimes hands you XLOOKUP
VLOOKUP always searches the first column of its range,
and can only hand back columns to that column's right. When the dropdown's
values live anywhere else in the table, no column number fixes it — the
formula has to name the search column and the return column separately,
which is exactly what XLOOKUP does. Same table, same answer,
different engine; this page picks the one your layout needs.
The other quiet failure is the empty dropdown. Clearing a chip clears the
value, not the rule — and a lookup with nothing to search for
returns #N/A in every cell that reads it. Wrapping the formula
in IFERROR(…, "") turns that into a clean blank, which is why
it is the default here.
Seeing it done
The channel builds this exact form on camera — the Data validation rule, the first pick, the VLOOKUP landing the price, and the beat where clearing the dropdown shows the #N/A this page's default guards against. The default formula this page emits is the one that runs there. The video is How to Auto-Populate Cells Based on a Dropdown Selection.