diff --git a/crates/ui-egui/src/grid.rs b/crates/ui-egui/src/grid.rs
index 8acd5bc00..9874c3740 100644
--- a/crates/ui-egui/src/grid.rs
+++ b/crates/ui-egui/src/grid.rs
@@ -2745,7 +2745,9 @@ fn in_cell_editor(app: &mut SheetApp, ui: &mut egui::Ui, geo: &Geo, sh: &Sheet,
         (rect.width(), (wrapped.size().y.max(size * 1.3 * lines) + 4.0).max(rect.height()))
     } else {
         let text_w = ui.painter().layout_no_wrap(ed.text.clone(), font.clone(), Color32::BLACK).size().x;
-        ((text_w + 14.0).max(rect.width()).min(geo.cells.right() - rect.left()), (size * 1.3 * lines + 4.0).max(rect.height()))
+        // Excel keeps the cell's height for one line and only grows for extra lines.
+        let h = if lines > 1.0 { (size * 1.3 * lines + 4.0).max(rect.height()) } else { rect.height() };
+        ((text_w + 14.0).max(rect.width()).min(geo.cells.right() - rect.left()), h)
     };
     // Grows to the left on a right-to-left sheet.
     let erect = geo.mirror_rect(Rect::from_min_size(rect.min, vec2(w, h)));
diff --git a/crates/ui-egui/tests/in_cell_editor_size.rs b/crates/ui-egui/tests/in_cell_editor_size.rs
new file mode 100644
index 000000000..4d82cd711
--- /dev/null
+++ b/crates/ui-egui/tests/in_cell_editor_size.rs
@@ -0,0 +1,87 @@
+//! The in-cell editor covers the edited cell exactly, as in Excel, at every zoom (#1755).
+
+use egui::{Color32, Event, Modifiers, PointerButton, Rect, Shape};
+use gridcraft_engine::Session;
+use gridcraft_engine::core::CellRef;
+use gridcraft_ui_egui::{SheetApp, grid::Geo};
+use serde_json::json;
+
+type Harness = egui_kittest::Harness<'static, SheetApp>;
+
+fn harness() -> Harness {
+    let mut session = Session::new();
+    session.new_workbook();
+    let mut h = egui_kittest::Harness::builder().with_size(egui::vec2(1200.0, 800.0)).build_ui_state(
+        |ui, app: &mut SheetApp| {
+            app.logic(ui.ctx());
+            app.ui(ui);
+        },
+        SheetApp::new(session, Default::default()),
+    );
+    h.run_steps(4);
+    h
+}
+
+fn cell_rect(h: &Harness, cell: &str) -> Rect {
+    let app = h.state();
+    let sheet = app.session.active().unwrap().wb.active().unwrap();
+    let geo = Geo::new(sheet, app.grid.rect.unwrap(), app.view().scroll);
+    geo.cell_rect(sheet, CellRef::parse(cell).unwrap())
+}
+
+fn click_cell(h: &mut Harness, cell: &str) {
+    let pos = cell_rect(h, cell).center();
+    h.input_mut().events.extend([
+        Event::PointerMoved(pos),
+        Event::PointerButton { pos, button: PointerButton::Primary, pressed: true, modifiers: Modifiers::NONE },
+        Event::PointerButton { pos, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE },
+    ]);
+    h.run_steps(2);
+}
+
+fn type_text(h: &mut Harness, text: &str) {
+    h.input_mut().events.push(Event::Text(text.into()));
+    h.run_steps(3);
+}
+
+/// The white editor background painted from the cell's top-left corner.
+fn editor_rect(h: &Harness, cell: Rect) -> Rect {
+    h.output()
+        .shapes
+        .iter()
+        .filter_map(|s| match &s.shape {
+            Shape::Rect(r) if r.fill == Color32::WHITE && (r.rect.min - cell.min).length() < 0.01 => Some(r.rect),
+            _ => None,
+        })
+        .next_back()
+        .expect("in-cell editor background")
+}
+
+fn assert_close(a: Rect, b: Rect, what: &str) {
+    assert!((a.min - b.min).length() < 0.01 && (a.max - b.max).length() < 0.01, "{what}: editor {a:?} must match cell {b:?}");
+}
+
+#[test]
+fn editor_matches_the_cell_at_every_zoom() {
+    for zoom in [50u16, 100, 200, 400] {
+        let mut h = harness();
+        h.state_mut().run("view.zoom", json!({"percent": zoom})).unwrap();
+        h.run_steps(3);
+        click_cell(&mut h, "B2");
+        type_text(&mut h, "abc");
+        assert!(h.state().editor.is_some());
+        let cell = cell_rect(&h, "B2");
+        assert_close(editor_rect(&h, cell), cell, &format!("zoom {zoom}"));
+    }
+}
+
+#[test]
+fn one_long_line_widens_the_editor_but_keeps_the_row_height() {
+    let mut h = harness();
+    click_cell(&mut h, "B2");
+    type_text(&mut h, "a much longer line of text than the cell can hold");
+    let cell = cell_rect(&h, "B2");
+    let ed = editor_rect(&h, cell);
+    assert!(ed.width() > cell.width() + 1.0, "long text widens the editor: {ed:?} vs {cell:?}");
+    assert!((ed.height() - cell.height()).abs() < 0.01, "one line keeps the row height: {ed:?} vs {cell:?}");
+}