matplotlib · Raab70 · Dec 27, 2017 · Dec 27, 2017 · Dec 27, 2017 · Dec 27, 2017
diff --git a/doc/users/next_whats_new/2017-12-27_legend_title_size_rc.rst b/doc/users/next_whats_new/2017-12-27_legend_title_size_rc.rst
@@ -0,0 +1,13 @@
+Legend Title Size rc parameter
+------------------------------
+
+A new rc parameter has been added as an option in matplotlibrc allowing you to explicitly control the font size of the legend title.
+The default option is ``inherit`` which reverts to the previous behavior of inheriting font size from ``font.size``.
+
+``legend.titlesize = 'large'``
+
+.. code-block:: python
+
+    import matplotlib.rcParams as rcParams
+
+    rcParams['legend.titlesize'] = 'large'
diff --git a/lib/matplotlib/legend.py b/lib/matplotlib/legend.py
@@ -713,7 +713,10 @@ def __init__(self, parent, handles, labels,
             self.get_frame().set_alpha(framealpha)
 
         self._loc = loc
-        self.set_title(title)
+        if rcParams["legend.titlesize"] == 'inherit':
+            self.set_title(title)
+        else:
+            self.set_title(title, prop={"size": rcParams["legend.titlesize"]})
         self._last_fontsize_points = self._fontsize
         self._draggable = None
 

diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -440,6 +440,13 @@ def validate_fontsize(s):
 validate_fontsizelist = _listify_validator(validate_fontsize)
 
 
+def validate_fontsize_or_inherit(s):
+    'return a valid fontsize arg'
+    if s == 'inherit':
+        return s
+    return validate_fontsize(s)
+
+
 def validate_font_properties(s):
     parse_fontconfig_pattern(s)
     return s
@@ -1178,6 +1185,7 @@ def _validate_linestyle(ls):
     # the number of points in the legend line for scatter
     'legend.scatterpoints': [1, validate_int],
     'legend.fontsize': ['medium', validate_fontsize],
+    'legend.titlesize': ['inherit', validate_fontsize_or_inherit],
      # the relative size of legend markers vs. original
     'legend.markerscale': [1.0, validate_float],
     'legend.shadow': [False, validate_bool],

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
@@ -191,6 +191,29 @@ def test_rc():
               title="My legend")
 
 
+def test_rc_title_size():
+    test_legend_title_size = 18.0
+    mpl.rcParams['legend.titlesize'] = test_legend_title_size
+    plt.figure()
+    ax = plt.subplot(121)
+    ax.scatter(np.arange(10), np.arange(10, 0, -1), label='two')
+    leg = ax.legend(loc="center left", bbox_to_anchor=[1.0, 0.5],
+                    title="My legend")
+    assert leg.get_title().get_fontsize() == test_legend_title_size
+
+
+def test_rc_title_size_inherit():
+    test_legend_title_size = 18.0
+    mpl.rcParams['legend.titlesize'] = 'inherit'
+    mpl.rcParams['font.size'] = test_legend_title_size
+    plt.figure()
+    ax = plt.subplot(121)
+    ax.scatter(np.arange(10), np.arange(10, 0, -1), label='one')
+    leg = ax.legend(loc="center left", bbox_to_anchor=[1.0, 0.5],
+                    title="My Inherited Legend Title")
+    assert leg.get_title().get_fontsize() == test_legend_title_size
+
+
 @image_comparison(baseline_images=['legend_expand'], remove_text=True)
 def test_legend_expand():
     'Test expand mode'

diff --git a/matplotlibrc.template b/matplotlibrc.template
@@ -414,6 +414,7 @@ backend      : $TEMPLATE_BACKEND
 #legend.scatterpoints : 1        # number of scatter points
 #legend.markerscale   : 1.0      # the relative size of legend markers vs. original
 #legend.fontsize      : medium
+#legend.titlesize     : inherit    # fontsize of the legend title, or inherit from font.size
 # Dimensions as fraction of fontsize:
 #legend.borderpad     : 0.4      # border whitespace
 #legend.labelspacing  : 0.5      # the vertical space between the legend entries