diff --git a/crates/engine/src/cmd/mod.rs b/crates/engine/src/cmd/mod.rs
index 50865a2b7..5365d1403 100644
--- a/crates/engine/src/cmd/mod.rs
+++ b/crates/engine/src/cmd/mod.rs
@@ -482,6 +482,10 @@ pub fn auto_row_height(wb: &mut Workbook, si: usize, row: u32) {
     }
     let mut need: f32 = default;
     for (c, cell) in sh.cells.row(row, 0, gridcraft_core::MAX_COLS - 1) {
+        // Merged cells never auto-fit their rows, like Excel (column autofit skips them too).
+        if sh.merge_at(CellRef::new(row, c)).is_some_and(|m| !m.is_single()) {
+            continue;
+        }
         let st = wb.styles.get(cell.style);
         let size = st.font.size;
         let line = (size * 1.8).round().max(default * size / gridcraft_model::DEFAULT_FONT_SIZE);
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 07656aacb..2da46caed 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -1166,6 +1166,33 @@ fn open_leaves_plain_workbooks_untouched() {
     assert!(sh.rows.values().all(|i| i.size.is_none()), "no row gains a height entry");
 }
 
+/// Merged cells never auto-fit their rows, like Excel (issue #1605): a wrapped merged
+/// header keeps the default height instead of growing to its column-A wrap width, while an
+/// unmerged wrapped cell in the same sheet still fits.
+#[test]
+fn autofit_skips_merged_cells() {
+    let mut s = s();
+    s.execute("cell.set", json!({"cell": "A1", "input": "This is a long sentence that should wrap across the merged width of five columns"}))
+        .unwrap();
+    s.execute("home.mergeCells", json!({"range": "A1:E1"})).unwrap();
+    s.execute("home.wrapText", json!({"range": "A1:E1", "on": true})).unwrap();
+    s.execute("cell.set", json!({"cell": "A3", "input": "This is a long sentence that should wrap across the merged width of five columns"}))
+        .unwrap();
+    s.execute("home.wrapText", json!({"range": "A3", "on": true})).unwrap();
+    let sh = s.doc().unwrap().wb.active().unwrap();
+    assert!(sh.rows.get(&0).is_none_or(|i| i.size.is_none()), "merged wrap must not auto-fit row 1, got {:?}", sh.rows.get(&0));
+    assert!(sh.rows.get(&2).is_some_and(|i| i.size.is_some_and(|h| h > 15.0)), "unmerged wrap still fits its row");
+    // The save writes no height for the merged row.
+    let r = s.execute("file.saveBytes", json!({"format": "xlsx"})).unwrap();
+    let bytes = crate::io::base64_decode(r["base64"].as_str().unwrap()).unwrap();
+    let mut zip = zip::ZipArchive::new(std::io::Cursor::new(bytes)).unwrap();
+    let mut xml = String::new();
+    std::io::Read::read_to_string(&mut zip.by_name("xl/worksheets/sheet1.xml").unwrap(), &mut xml).unwrap();
+    let row1 = xml.split("<row").skip(1).map(|r| format!("<row{r}")).find(|r| r.starts_with("<row r=\"1\"")).unwrap();
+    assert!(!row1.split('>').next().unwrap().contains("ht="), "merged row 1 must be saved without ht, got {row1}");
+    assert!(xml.contains("<mergeCell ref=\"A1:E1\"/>"), "the merge itself is saved");
+}
+
 #[test]
 fn tables_and_structured_refs() {
     let mut s = s();