matplotlib · ayshih · May 18, 2026 · May 19, 2026 · anntzer · May 19, 2026
diff --git a/lib/matplotlib/gridspec.py b/lib/matplotlib/gridspec.py
@@ -187,6 +187,11 @@ def get_grid_positions(self, fig):
 
         fig_tops, fig_bottoms = (top - cell_hs).reshape((-1, 2)).T
         fig_lefts, fig_rights = (left + cell_ws).reshape((-1, 2)).T
+
+        # avoid floating-point precision where A + (B - A) does not equal B
+        fig_bottoms[-1] = bottom
+        fig_rights[-1] = right
+
         return fig_bottoms, fig_tops, fig_lefts, fig_rights
 
     @staticmethod

diff --git a/...atplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout10.png b/...atplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout10.png
diff --git a/lib/matplotlib/tests/baseline_images/test_patheffects/patheffect3.png b/lib/matplotlib/tests/baseline_images/test_patheffects/patheffect3.png
diff --git a/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout2.png b/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout2.png
diff --git a/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout3.png b/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout3.png
diff --git a/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout6.png b/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout6.png
diff --git a/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout9.png b/lib/matplotlib/tests/baseline_images/test_tightlayout/tight_layout9.png
diff --git a/lib/matplotlib/tests/test_transforms.py b/lib/matplotlib/tests/test_transforms.py
@@ -927,7 +927,7 @@ def test_str_transform():
                          [-- --]])))),
         BboxTransformTo(
             TransformedBbox(
-                Bbox(x0=0.125, y0=0.09999999999999998, x1=0.9, y1=0.9),
+                Bbox(x0=0.125, y0=0.1, x1=0.9, y1=0.9),
                 BboxTransformTo(
                     TransformedBbox(
                         Bbox(x0=0.0, y0=0.0, x1=8.0, y1=6.0),