diff --git a/crates/ui-egui/src/midi_editor.rs b/crates/ui-egui/src/midi_editor.rs
index e69d6255..b8acb62c 100644
--- a/crates/ui-egui/src/midi_editor.rs
+++ b/crates/ui-egui/src/midi_editor.rs
@@ -84,6 +84,19 @@ pub fn show(app: &mut SoundApp, ui: &mut Ui) {
         regular(11.0),
         t.text_dim,
     );
+    let grid_ticks = match app.engine.session().edit.grid {
+        soundcraft_time::GridValue::Note { value, dotted, triplet } => {
+            let mut g = value.ticks();
+            if dotted {
+                g = g * 3 / 2;
+            }
+            if triplet {
+                g = g * 2 / 3;
+            }
+            g.max(1)
+        }
+        _ => TICKS_PER_QUARTER / 4,
+    };
     // Header toolbar: whole-clip MIDI operations.
     let bar = Rect::from_min_max(pos2(header.max.x - 330.0, header.min.y + 1.0), pos2(header.max.x - 6.0, header.max.y - 1.0));
     let mut tb = ui.new_child(egui::UiBuilder::new().max_rect(bar).layout(egui::Layout::right_to_left(egui::Align::Center)));
@@ -99,7 +112,7 @@ pub fn show(app: &mut SoundApp, ui: &mut Ui) {
         op = Some(("event.change_velocity", json!({"add": 10})));
     }
     if tb.small_button("Quantize").on_hover_text("Quantize to the grid").clicked() {
-        op = Some(("event.quantize", json!({"grid": "1/16", "strength": 100})));
+        op = Some(("event.quantize", json!({"grid": grid_ticks, "strength": 100})));
     }
     if let Some((id, mut p)) = op {
         p["clips"] = json!([cid.0]);
@@ -109,19 +122,6 @@ pub fn show(app: &mut SoundApp, ui: &mut Ui) {
     let sr = s.sample_rate;
     let base_tick = s.tempo.samples_to_ticks(clip.start, sr);
     let len_ticks = (s.tempo.samples_to_ticks(clip.end(), sr) - base_tick).max(1);
-    let grid_ticks = match s.edit.grid {
-        soundcraft_time::GridValue::Note { value, dotted, triplet } => {
-            let mut g = value.ticks();
-            if dotted {
-                g = g * 3 / 2;
-            }
-            if triplet {
-                g = g * 2 / 3;
-            }
-            g.max(1)
-        }
-        _ => TICKS_PER_QUARTER / 4,
-    };
     let roll = Rect::from_min_max(pos2(full.min.x + KEY_W, header.max.y), pos2(full.max.x - 4.0, full.max.y - VEL_H - 4.0));
     let keys = Rect::from_min_max(pos2(full.min.x, roll.min.y), pos2(roll.min.x, roll.max.y));
     let vel = Rect::from_min_max(pos2(roll.min.x, roll.max.y + 4.0), pos2(roll.max.x, full.max.y - 2.0));
diff --git a/crates/ui-egui/tests/midi_quantize.rs b/crates/ui-egui/tests/midi_quantize.rs
new file mode 100644
index 00000000..de9b0b33
--- /dev/null
+++ b/crates/ui-egui/tests/midi_quantize.rs
@@ -0,0 +1,38 @@
+//! The MIDI Editor's Quantize button snaps to the grid the editor shows.
+use egui::vec2;
+use egui_kittest::{Harness, kittest::Queryable};
+use serde_json::json;
+use soundcraft_ui_egui::{Services, SoundApp};
+
+fn quantize_on(grid: &str) -> i64 {
+    let mut app = SoundApp::new(soundcraft_engine::Engine::default(), None, Services::default());
+    app.run("track.new", json!({"name": "Grid Check", "kind": "midi"})).unwrap();
+    let clip = app.run("midi.new_clip", json!({"track": "Grid Check", "start": 0, "end": 96_000})).unwrap()["clip"].clone();
+    app.run("midi.note_add", json!({"clip": clip, "pitch": 60, "start_ticks": 300, "length_ticks": 240})).unwrap();
+    app.run("edit.select", json!({"clips": [clip]})).unwrap();
+    app.run("view.grid", json!({"value": grid})).unwrap();
+    app.ui.show_midi_editor = true;
+    let mut h = Harness::builder().with_size(vec2(1600.0, 1000.0)).build_ui_state(
+        |ui, app: &mut SoundApp| {
+            app.logic(&ui.ctx().clone());
+            app.ui(ui);
+        },
+        app,
+    );
+    h.run_steps(5);
+    h.get_by_label("Quantize").click();
+    h.run_steps(3);
+    let notes = h.state_mut().run("midi.notes", json!({"clip": clip})).unwrap();
+    assert_eq!(notes["notes"][0]["length"], 240, "{notes}");
+    notes["notes"][0]["start"].as_i64().unwrap()
+}
+
+#[test]
+fn quantize_follows_a_quarter_note_grid() {
+    assert_eq!(quantize_on("1/4"), 0);
+}
+
+#[test]
+fn quantize_follows_a_sixteenth_note_grid() {
+    assert_eq!(quantize_on("1/16"), 240);
+}