matplotlib · story645 · Sep 8, 2026 · Sep 3, 2026 · Sep 3, 2026 · Sep 5, 2026
diff --git a/doc/release/next_whats_new/new_barcontainer_properties.rst b/doc/release/next_whats_new/new_barcontainer_properties.rst
@@ -0,0 +1,16 @@
+``BarContainer`` properties and attributes
+------------------------------------------
+
+`.BarContainer` gained a new `~.BarContainer.widths` property. It returns a
+list of the widths of the individual bars in the container (the dimension
+perpendicular to the bar height).
+
+For standard bar plots (e.g. created by `.Axes.bar` or `.Axes.barh`), this
+reflects the width of each bar in the plot. For grouped bar plots (e.g. created
+by `.Axes.grouped_bar`), each `~.BarContainer` represents one group of bars across
+categories, so `~.BarContainer.widths` returns the width of each
+individual bar in that group, rather than the total width of the entire group.
+
+Additionally, `.BarContainer` gained a new ``group_positions`` attribute, which
+exposes the center positions of the bar groups if the container is part of a
+grouped bar plot (e.g. created by `.Axes.grouped_bar`), or ``None`` otherwise.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -3363,6 +3363,7 @@ def grouped_bar(self, heights, *, positions=None, group_spacing=1.5, bar_spacing
             else:
                 bc = self.barh(lefts, hs, height=bar_width, align="edge",
                                label=label, color=color, **styles, **kwargs)
+            bc.group_positions = group_centers
             bar_containers.append(bc)
 
         if tick_labels is not None:

diff --git a/lib/matplotlib/container.py b/lib/matplotlib/container.py
@@ -63,14 +63,20 @@ class BarContainer(Container):
         If 'vertical', the bars are assumed to be vertical.
         If 'horizontal', the bars are assumed to be horizontal.
 
+    group_positions : None or array-like
+        The center positions of the bar groups if the container is part of a
+        grouped bar plot (e.g. created by `.Axes.grouped_bar`). *None* otherwise.
+
+        .. versionadded:: 3.12
     """
 
     def __init__(self, patches, errorbar=None, *, datavalues=None,
-                 orientation=None, **kwargs):
+                 orientation=None, group_positions=None, **kwargs):
         self.patches = patches
         self.errorbar = errorbar
         self.datavalues = datavalues
         self.orientation = orientation
+        self.group_positions = group_positions
         super().__init__(patches, **kwargs)
 
     @property
@@ -115,6 +121,20 @@ def position_centers(self):
         else:
             raise ValueError("orientation must be 'vertical' or 'horizontal'.")
 
+    @property
+    def widths(self):
+        """
+        Return the widths of the bars.
+
+        .. versionadded:: 3.12
+        """
+        if self.orientation == 'vertical':
+            return [p.get_width() for p in self.patches]
+        elif self.orientation == 'horizontal':
+            return [p.get_height() for p in self.patches]
+        else:
+            raise ValueError("orientation must be 'vertical' or 'horizontal'.")
+
 
 class ErrorbarContainer(Container):
     """

diff --git a/lib/matplotlib/container.pyi b/lib/matplotlib/container.pyi
@@ -25,13 +25,15 @@ class BarContainer(Container):
     errorbar: None | ErrorbarContainer
     datavalues: None | ArrayLike
     orientation: None | Literal["vertical", "horizontal"]
+    group_positions: None | ArrayLike
     def __init__(
         self,
         patches: list[Rectangle],
         errorbar: ErrorbarContainer | None = ...,
         *,
         datavalues: ArrayLike | None = ...,
         orientation: Literal["vertical", "horizontal"] | None = ...,
+        group_positions: ArrayLike | None = ...,
         **kwargs
     ) -> None: ...
     @property
@@ -40,6 +42,8 @@ class BarContainer(Container):
     def tops(self) -> list[float]: ...
     @property
     def position_centers(self) -> list[float]: ...
+    @property
+    def widths(self) -> list[float]: ...
 
 class ErrorbarContainer(Container):
     lines: tuple[Line2D, tuple[Line2D, ...], tuple[LineCollection, ...]]

diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -2296,6 +2296,8 @@ def test_grouped_bar_return_value():
     for bc in ret.bar_containers:
         assert isinstance(bc, BarContainer)
         assert bc in ax.containers
+        np.testing.assert_array_equal(bc.group_positions, [0, 1, 2])
+        assert bc.widths == [p.get_width() for p in bc.patches]
 
     ret.remove()
     for bc in ret.bar_containers: