diff --git a/crates/engine/src/cmd/mod.rs b/crates/engine/src/cmd/mod.rs
index 5365d1403..70f20fce6 100644
--- a/crates/engine/src/cmd/mod.rs
+++ b/crates/engine/src/cmd/mod.rs
@@ -488,7 +488,9 @@ pub fn auto_row_height(wb: &mut Workbook, si: usize, row: u32) {
         }
         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);
+        // Scaled from an 11pt row's height, not the sheet's default: a sheet whose default
+        // already fits a bigger font (21pt rows for 16pt text) would otherwise scale it twice.
+        let line = (size * 1.8).round().max(gridcraft_model::DEFAULT_ROW_HEIGHT * size / gridcraft_model::DEFAULT_FONT_SIZE);
         let mut lines = 1.0f32;
         if !cell.value.is_empty() || cell.formula.is_some() {
             let text = crate::display::cell_text(wb, sh, CellRef::new(row, c));
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 2da46caed..c49e67540 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -1193,6 +1193,26 @@ fn autofit_skips_merged_cells() {
     assert!(xml.contains("<mergeCell ref=\"A1:E1\"/>"), "the merge itself is saved");
 }
 
+#[test]
+fn open_fits_big_font_rows_from_the_font_not_the_sheet_default() {
+    // Excel saves a sheet whose rows hold 16pt text with a 21pt (28px) default row height and no
+    // `ht` on rows of that height. Those rows already fit their font: they open at about 28px,
+    // not scaled up again by 16/11 to 41px.
+    let mut wb = gridcraft_model::Workbook::new();
+    let big = wb.styles.derive(gridcraft_model::StyleId::DEFAULT, |s| s.font.size = 16.0);
+    let sh = wb.sheet_mut(0).unwrap();
+    sh.default_row_height = 28.0;
+    sh.set_value(CellRef::new(4, 0), Value::text("SANTANDER"));
+    sh.set_style(CellRef::new(4, 0), big);
+    let bytes = gridcraft_xlsx::write_xlsx(&wb).unwrap();
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "tall-default.xlsx", "base64": crate::io::base64_encode(&bytes)})).unwrap();
+    let sh = s.doc().unwrap().wb.active().unwrap();
+    assert_eq!(sh.default_row_height, 28.0);
+    let h = sh.row_height(4);
+    assert!((28.0..30.0).contains(&h), "a 16pt row on a 28px-default sheet opens at about 28px, got {h}");
+}
+
 #[test]
 fn tables_and_structured_refs() {
     let mut s = s();