diff --git a/crates/tools/src/addons/measure_inspect.rs b/crates/tools/src/addons/measure_inspect.rs
index d46edb6c6..1ea8a9324 100644
--- a/crates/tools/src/addons/measure_inspect.rs
+++ b/crates/tools/src/addons/measure_inspect.rs
@@ -95,12 +95,7 @@ impl Tool for MeasureInspectTool {
             }
             PointerKind::Drag | PointerKind::Up if self.dragging => {
                 if let Some((a, _)) = self.line {
-                    let b = if ev.mods.shift {
-                        a + vectorcraft_geom::constrain_angle_from(ev.pos - a, 45.0, cx.constrain_angle)
-                    } else {
-                        crate::guides::snap_draw(cx, ev.pos, &[]).0
-                    };
-                    self.line = Some((a, b));
+                    self.line = Some((a, crate::xform::measure_end_point(cx, a, ev.pos, ev.mods.shift)));
                 }
                 self.dragging = ev.kind == PointerKind::Drag;
             }
@@ -213,4 +208,23 @@ mod tests {
         assert_eq!(t.options(), Value::Null);
         assert_eq!(area_label(Unit::Points, 2.0), "2.00 pt²");
     }
+
+    /// A Shift-drag snaps its end point to the grid, then projects it onto its 45° step.
+    #[test]
+    fn shift_drag_snaps_its_end_point() {
+        let (d, _) = doc_with_rect();
+        let (s, p) = (Selection::default(), paint());
+        let mut cx = cx(&d, &s, &p);
+        cx.smart_guides = false;
+        cx.snap_to_grid = true;
+        let shift = Mods { shift: true, ..Mods::default() };
+        let mut t = MeasureInspectTool::default();
+        // (37.3, 12.1) snaps to (36, 9) on the 9 pt grid, and Shift keeps it at 0°: (36, 0).
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Drag, 37.3, 12.1).with_mods(shift));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 37.3, 12.1).with_mods(shift));
+        let o = t.options();
+        assert!((o["distance"].as_f64().unwrap() - 36.0).abs() < 1e-9, "on the 9 pt grid: {o}");
+        assert!(o["dy"].as_f64().unwrap().abs() < 1e-9, "kept horizontal: {o}");
+    }
 }
diff --git a/crates/tools/src/xform.rs b/crates/tools/src/xform.rs
index de9c9c0cb..915eb35e8 100644
--- a/crates/tools/src/xform.rs
+++ b/crates/tools/src/xform.rs
@@ -22,6 +22,7 @@ pub use artboard::ArtboardTool;
 pub use eyedropper::EyedropperTool;
 pub use free::{DistortMode, FreeTransformTool};
 pub use gradient::GradientTool;
+pub(crate) use measure::end_point as measure_end_point;
 pub use measure::{MeasureTool, measure};
 pub use transform::{TransformKind, TransformTool};
 pub use wand::{LassoTool, MagicWandTool};
diff --git a/crates/tools/src/xform/measure.rs b/crates/tools/src/xform/measure.rs
index 3f2b350e0..140697dd6 100644
--- a/crates/tools/src/xform/measure.rs
+++ b/crates/tools/src/xform/measure.rs
@@ -23,6 +23,28 @@ pub fn measure(a: Point, b: Point) -> (f64, f64, f64, f64) {
     (d.hypot(), (-d.y).atan2(d.x).to_degrees() + 0.0, d.x, d.y)
 }
 
+/// The end of a measurement from `a` with the pointer at `p`: `p` snapped as a drawing tool snaps
+/// it. With Shift held, the end stays on the 45° step from the Constrain Angle nearest the
+/// pointer's direction: `p` is projected onto the step, then snapped along it as the Line Segment
+/// tool snaps a Shift-drawn end. With Snap to Point alone, the point `p` snaps to (an anchor, or
+/// in line with a ruler guide) is projected instead.
+pub(crate) fn end_point(cx: &ToolContext, a: Point, p: Point, shift: bool) -> Point {
+    if !shift {
+        return crate::guides::snap_draw(cx, p, &[]).0;
+    }
+    let d = vectorcraft_geom::constrain_angle_from(p - a, 45.0, cx.constrain_angle);
+    let len = d.hypot();
+    if len < 1e-12 {
+        return a;
+    }
+    let u = d / len;
+    let to_point = cx.snap_to_point && !(cx.smart_guides || cx.snap_to_grid || cx.snap_to_pixel);
+    let s = if to_point { crate::guides::snap_draw(cx, p, &[]).0 } else { p };
+    let q = a + u * (s - a).dot(u);
+    let leave = crate::guides::Leave::segment(cx, a, true);
+    crate::guides::PointSnap::new(cx, || crate::guides::Targets::collect(cx.doc, &[], None)).snap_from(cx, q, Some(&leave)).0
+}
+
 impl Tool for MeasureTool {
     fn id(&self) -> &'static str {
         "measure"
@@ -42,12 +64,7 @@ impl Tool for MeasureTool {
             }
             PointerKind::Drag | PointerKind::Up if self.dragging => {
                 if let Some((a, _)) = self.line {
-                    let b = if ev.mods.shift {
-                        a + vectorcraft_geom::constrain_angle_from(ev.pos - a, 45.0, cx.constrain_angle)
-                    } else {
-                        crate::guides::snap_draw(cx, ev.pos, &[]).0
-                    };
-                    self.line = Some((a, b));
+                    self.line = Some((a, end_point(cx, a, ev.pos, ev.mods.shift)));
                 }
                 self.dragging = ev.kind == PointerKind::Drag;
             }
@@ -141,6 +158,89 @@ mod tests {
         assert!(ov.iter().any(|o| matches!(o, Overlay::Line { .. })), "the measured line stays");
     }
 
+    /// A Shift-drag snaps its end point as a drag without Shift does, then projects it onto its
+    /// 45° step: onto the grid with Snap to Grid, in line with an anchor with Smart Guides. With
+    /// no snapping, the end is the pointer projected onto the step.
+    #[test]
+    fn shift_drag_snaps_its_end_point() {
+        let (d, _) = doc_with_rect();
+        let s = Selection::default();
+        let p = paint();
+        let mut cx = cx(&d, &s, &p);
+        cx.smart_guides = false;
+        cx.snap_to_grid = true;
+        let shift = Mods { shift: true, ..Mods::default() };
+        let mut t = MeasureTool::default();
+        // (37.3, 12.1) snaps to (36, 9) on the 9 pt grid, and Shift keeps it at 0°: (36, 0).
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Drag, 37.3, 12.1).with_mods(shift));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 37.3, 12.1).with_mods(shift));
+        let o = t.options();
+        assert!((o["distance"].as_f64().unwrap() - 36.0).abs() < 1e-9, "on the 9 pt grid: {o}");
+        assert!(o["dy"].as_f64().unwrap().abs() < 1e-9, "kept horizontal: {o}");
+        // Near 45°: (31.4, 27.7) snaps to (27, 27).
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 31.4, 27.7).with_mods(shift));
+        let o = t.options();
+        assert!((o["dx"].as_f64().unwrap() - 27.0).abs() < 1e-9, "{o}");
+        assert!((o["dy"].as_f64().unwrap() - 27.0).abs() < 1e-9, "{o}");
+        // No snapping: the pointer is projected onto 0°, so the measurement is 37.3 pt.
+        cx.snap_to_grid = false;
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 37.3, 12.1).with_mods(shift));
+        let o = t.options();
+        assert!((o["distance"].as_f64().unwrap() - 37.3).abs() < 1e-9, "{o}");
+        assert!(o["dy"].as_f64().unwrap().abs() < 1e-9, "{o}");
+        // Snap to Point alone: the end snaps to the anchor at (200, 200) and is projected onto
+        // 0°, so it ends in line with it: (200, 203).
+        assert!(cx.snap_to_point);
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 300.0, 203.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 201.0, 201.0).with_mods(shift));
+        let o = t.options();
+        assert!((o["dx"].as_f64().unwrap() + 100.0).abs() < 1e-9, "{o}");
+        assert!(o["dy"].as_f64().unwrap().abs() < 1e-9, "{o}");
+        // An anchor on the 45° step: the end lands on it.
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 101.0, 100.0).with_mods(shift));
+        let o = t.options();
+        assert!((o["dx"].as_f64().unwrap() - 100.0).abs() < 1e-9, "{o}");
+        assert!((o["dy"].as_f64().unwrap() - 100.0).abs() < 1e-9, "{o}");
+        // Smart Guides: from (300, 300), Shift keeps the end at 0° and it lands in line with x = 200.
+        cx.snap_to_grid = false;
+        cx.smart_guides = true;
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 300.0, 300.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Drag, 203.0, 303.0).with_mods(shift));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 203.0, 303.0).with_mods(shift));
+        let o = t.options();
+        assert!((o["distance"].as_f64().unwrap() - 100.0).abs() < 1e-9, "{o}");
+        assert!(o["dy"].as_f64().unwrap().abs() < 1e-9, "{o}");
+        // At 45°, the end slides along the step to where it meets x = 200: (200, 220).
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 300.0, 320.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 203.0, 222.5).with_mods(shift));
+        let o = t.options();
+        assert!((o["dx"].as_f64().unwrap() + 100.0).abs() < 1e-9, "{o}");
+        assert!((o["dy"].as_f64().unwrap() + 100.0).abs() < 1e-9, "{o}");
+    }
+
+    /// With Snap to Point alone, a Shift-drag's end slides along its 45° step to a ruler guide.
+    #[test]
+    fn shift_drag_meets_a_ruler_guide() {
+        let (mut d, _) = doc_with_rect();
+        d.guides.push(vectorcraft_doc::Guide::new(true, 50.0));
+        let s = Selection::default();
+        let p = paint();
+        let mut cx = cx(&d, &s, &p);
+        cx.smart_guides = false;
+        assert!(cx.snap_to_point);
+        let shift = Mods { shift: true, ..Mods::default() };
+        let mut t = MeasureTool::default();
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Down, 0.0, 0.0));
+        t.pointer(&cx, &PointerEvent::new(PointerKind::Up, 51.0, 49.0).with_mods(shift));
+        let o = t.options();
+        assert!((o["dx"].as_f64().unwrap() - 50.0).abs() < 1e-9, "{o}");
+        assert!((o["dy"].as_f64().unwrap() - 50.0).abs() < 1e-9, "{o}");
+    }
+
     /// Escape during a drag ends it and brings back the result of the drag before (none at
     /// first); the release after it measures nothing.
     #[test]