matplotlib · tsumon · Sep 16, 2026 · Sep 18, 2026 · Sep 18, 2026
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -2668,6 +2668,39 @@ def contains(self, mouseevent):
             t < y < t + self._pickradius)
         return inaxis, {}
 
+    def _get_ticklabel_bboxes(self, ticks, renderer):
+        # Top alignment normally preserves the padding from the Axes, but can
+        # give plain, horizontal labels different baselines when their measured
+        # ascents differ.  Only normalize groups that actually differ so that
+        # uniformly sized labels keep their existing position.
+        for labels in ([tick.label1 for tick in ticks],
+                       [tick.label2 for tick in ticks]):
+            layouts = []
+            for label in labels:
+                label._baseline_ascent = None
+                if (not label.get_visible()
+                        or not label.get_in_layout()
+                        or not label.get_text()
+                        or label.get_verticalalignment() != "top"
+                        or label.get_rotation() != 0
+                        or label.get_rotation_mode() == "anchor"):
+                    continue
+                _, line_layouts, _ = label._get_layout(renderer)
+                if len(line_layouts) != 1:
+                    continue
+                line, (_, ascent, _), _ = line_layouts[0]
+                _, ismath = label._preprocess_math(line)
+                if ismath is False:
+                    layouts.append((label, ascent))
+
+            ascents = [ascent for _, ascent in layouts]
+            if ascents and not np.allclose(ascents, ascents[0]):
+                baseline_ascent = min(ascents)
+                for label, _ in layouts:
+                    label._baseline_ascent = baseline_ascent
+
+        return super()._get_ticklabel_bboxes(ticks, renderer)
+
     def set_label_position(self, position):
         """
         Set the label position (top or bottom)

diff --git a/lib/matplotlib/tests/baseline_images/test_axes/bar_tick_label_multiple.png b/lib/matplotlib/tests/baseline_images/test_axes/bar_tick_label_multiple.png
diff --git a/...tests/baseline_images/test_axes/bar_tick_label_multiple_old_label_alignment.png b/...tests/baseline_images/test_axes/bar_tick_label_multiple_old_label_alignment.png
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/set_get_ticklabels.png b/lib/matplotlib/tests/baseline_images/test_axes/set_get_ticklabels.png
diff --git a/lib/matplotlib/tests/test_axis.py b/lib/matplotlib/tests/test_axis.py
@@ -1,5 +1,7 @@
 import numpy as np
 
+import pytest
+
 import matplotlib.pyplot as plt
 from matplotlib.axis import XTick
 from matplotlib.testing.decorators import check_figures_equal
@@ -11,6 +13,35 @@ def test_tick_labelcolor_array():
     XTick(ax, 0, labelcolor=np.array([1, 0, 0, 1]))
 
 
+def test_xtick_labels_share_baseline():
+    fig, ax = plt.subplots(figsize=(.5, .5), layout="constrained")
+    ax.set_xlim(-2, 3)
+    ax.set_xticks([0, 1])
+    ax.xaxis.set_major_formatter(
+        lambda x, pos: "pol." if x == 0 else str(int(x)))
+
+    fig.canvas.draw()
+    bboxes = [label.get_window_extent(fig.canvas.get_renderer())
+              for label in ax.get_xticklabels()]
+
+    assert bboxes[0].y0 == pytest.approx(bboxes[1].y0)
+
+
+def test_xtick_labels_with_matching_ascents_keep_top_alignment():
+    fig, axs = plt.subplots(2)
+    for ax, label in zip(axs, ["1", "foo"]):
+        ax.set_xticks([0, 1], [label, label])
+
+    fig.canvas.draw()
+    renderer = fig.canvas.get_renderer()
+    label_pads = [
+        ax.bbox.y0 - ax.get_xticklabels()[0].get_window_extent(renderer).y1
+        for ax in axs
+    ]
+
+    assert label_pads[0] == pytest.approx(label_pads[1])
+
+
 def test_axis_not_in_layout():
     fig1, (ax1_left, ax1_right) = plt.subplots(ncols=2, layout='constrained')
     fig2, (ax2_left, ax2_right) = plt.subplots(ncols=2, layout='constrained')

diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -563,13 +563,18 @@ def _get_layout(self, renderer):
                 xmax if halign == "right" else
                 (xmin + xmax) / 2  # halign == "center"
             )
-            offsety = (
-                ymin if valign == "bottom" else
-                ymax if valign == "top" else
-                (ymin + ymax) / 2 if valign == "center" else
-                ymin + descent if valign == "baseline" else
-                ymin + height_rot - baseline / 2  # valign == "center_baseline"
-            )
+            baseline_ascent = getattr(self, "_baseline_ascent", None)
+            if (valign == "top" and len(lines) == 1 and angle == 0
+                    and baseline_ascent is not None):
+                offsety = ymax + baseline_ascent - baseline
+            else:
+                offsety = (
+                    ymin if valign == "bottom" else
+                    ymax if valign == "top" else
+                    (ymin + ymax) / 2 if valign == "center" else
+                    ymin + descent if valign == "baseline" else
+                    ymin + height_rot - baseline / 2  # valign == "center_baseline"
+                )
         else:
             xmin1, ymin1 = corners_horiz[0]
             xmax1, ymax1 = corners_horiz[2]