matplotlib
diff --git a/‎lib/matplotlib/axes/_axes.py
Lines changed: 26 additions & 13 deletions b/‎lib/matplotlib/axes/_axes.py
Lines changed: 26 additions & 13 deletions
@@ -2063,6 +2063,19 @@ def step(self, x, y, *args, where='pre', **kwargs):
         kwargs['drawstyle'] = 'steps-' + where
         return self.plot(x, y, *args, **kwargs)
 
+    @staticmethod
+    def _convert_dx(x0, x, dx, convert):
+        """ Small helper to do logic of width conversion flexibly """
+        try:
+            # attempt to add the width to x0; this works for
+            # datetime+timedelta, for instance
+            dx = convert(x0 + dx) - x
+        except (TypeError, AttributeError):
+            # but doesn't work for 'string' + float, so just
+            # see if the converter works on the float.
+            dx = convert(dx)
+        return dx
+
     @_preprocess_data(replace_names=["x", "left",
                                      "height", "width",
                                      "y", "bottom",
@@ -2232,23 +2245,25 @@ def bar(self, x, height, width=0.8, bottom=None, *, align="center",
         else:
             raise ValueError('invalid orientation: %s' % orientation)
 
+        x, height, width, y, linewidth = np.broadcast_arrays(
+            # Make args iterable too.
+            np.atleast_1d(x), height, width, y, linewidth)
+
         # lets do some conversions now since some types cannot be
         # subtracted uniformly
         if self.xaxis is not None:
+            x0 = x
             x = self.convert_xunits(x)
-            width = self.convert_xunits(width)
+            width = self._convert_dx(x0, x, width, self.convert_xunits)
             if xerr is not None:
-                xerr = self.convert_xunits(xerr)
+                xerr = self._convert_dx(x0, x, xerr, self.convert_xunits)
 
         if self.yaxis is not None:
+            y0 = y
             y = self.convert_yunits(y)
-            height = self.convert_yunits(height)
+            height = self._convert_dx(y0, y, height, self.convert_yunits)
             if yerr is not None:
-                yerr = self.convert_yunits(yerr)
-
-        x, height, width, y, linewidth = np.broadcast_arrays(
-            # Make args iterable too.
-            np.atleast_1d(x), height, width, y, linewidth)
+                yerr = self._convert_dx(y0, y, yerr, self.convert_yunits)
 
         # Now that units have been converted, set the tick locations.
         if orientation == 'vertical':
@@ -2528,11 +2543,9 @@ def broken_barh(self, xranges, yrange, **kwargs):
         xnew = []
         for xr in xranges:
             # convert the absolute values, not the x and dx...
-            x0 = [self.convert_xunits(xr[0]),
-                  self.convert_xunits(xr[0]+xr[1])]
-            # make a dx again...
-            x0[1] = x0[1] - x0[0]
-            xnew.append(x0)
+            x0 = self.convert_xunits(xr[0])
+            x1 = self._convert_dx(xr[0], x0, xr[1], self.convert_xunits)
+            xnew.append((x0, x1))
 
         yrange = self.convert_yunits(yrange)