Merge cells

A merged range renders, selects, and navigates as one spanning cell; merging clears every cell but the top-left, and undoes/redoes as one command.

What it does

Select a range and click the toolbar's Merge cells split button (⧉) to collapse it into one spanning cell — matching Google Sheets' Format ▸ Merge cells. The icon itself merges all (one click); its chevron opens a dropdown with Merge all / Merge vertically / Merge horizontally / Unmerge — Merge vertically collapses EACH COLUMN of the selection into its own top-to-bottom span (a 3-column selection produces 3 independent merges, not one big rect); Merge horizontally is the row analogue. Unavailable options grey out rather than disappear: Merge vertically for a single-row selection, Merge horizontally for a single-column selection, Unmerge when the active cell isn't part of a merge.

If any cell other than a resulting merge's own top-left carries content, an in-app "Heads up!" dialog warns that merging will clear it — "Merging cells will only preserve the top-left value. Merge anyway?" — with a "Don't show this again for 5 minutes" checkbox alongside Cancel (aborts) and OK (merges). This is a real, testable DOM element — [data-testid="merge-confirm-dialog"] — not a native window.confirm; the split-button dropdown, the keyboard/headless command surface, and every merge mode all route through the same dialog. Click Unmerge to restore independent cells — the anchor keeps its value, the others stay blank (their prior content was already cleared when the merge was created; unmerge does not resurrect it).

Click any cell inside a merged range and the whole merge is selected as one unit — the name box and formula bar read the merge's top-left address and content. Arrow keys move past a merge as a unit: arrowing into it from any side selects the whole merge, and arrowing again exits past its far edge rather than stepping cell-by-cell through the interior.

Merging a range that overlaps an existing merge auto-unmerges the conflicting merge first, then merges the new, larger range as one — no error, no refusal.

Try it

Verified behavior

Matches Google Sheets: In Google Sheets, Format ▸ Merge cells is a split control offering Merge all / Merge vertically (one merge per COLUMN of the selection) / Merge horizontally (one merge per ROW) / Unmerge. If any cell OTHER than a resulting merge's own top-left carries content, Sheets warns — an in-app "Heads up!" dialog reading "Merging cells will only preserve the top-left value. Merge anyway?", with a "Don't show this again for 5 minutes" checkbox alongside Cancel/OK — before clearing them; a range with content only in the surviving anchor cell(s) merges silently. Selecting any cell inside a merge selects the WHOLE merge as one unit (the name box / formula bar show the top-left anchor's address); arrow-key navigation moves PAST a merge as a unit rather than cell-by-cell through its interior. Merging a range that overlaps an existing merge auto-unmerges the conflicting merge(s) first, then merges the new (larger) range as one — no error. Unmerging restores independent cells but does NOT resurrect content cleared at merge time — the anchor keeps its current value, every other cell in the old merge stays blank.