diff --git a/src/calibre/ebooks/pdf/html_writer.py b/src/calibre/ebooks/pdf/html_writer.py
index 8552a89286..761571a724 100644
--- a/src/calibre/ebooks/pdf/html_writer.py
+++ b/src/calibre/ebooks/pdf/html_writer.py
@@ -657,6 +657,22 @@ class Range(object):
         return len(self.widths) == 1
 
 
+def all_glyph_ids_in_w_arrays(arrays):
+    ans = set()
+    for w in arrays:
+        i = 0
+        while i + 1 < len(w):
+            elem = w[i]
+            next_elem = w[i+1]
+            if isinstance(next_elem, list):
+                ans |= set(range(elem, elem + len(next_elem)))
+                i += 2
+            else:
+                ans |= set(range(elem, next_elem + 1))
+                i += 3
+    return sorted(ans)
+
+
 def merge_w_arrays(arrays):
     ranges = []
     for w in arrays:
@@ -822,10 +838,18 @@ def merge_font(fonts):
     cmaps = list(filter(None, (f['ToUnicode'] for f in t0_fonts)))
     if cmaps:
         t0_font['ToUnicode'] = as_bytes(merge_cmaps(cmaps))
-    for key in ('W', 'W2'):
-        arrays = tuple(filter(None, (f[key] for f in descendant_fonts)))
-        base_font[key] = merge_w_arrays(arrays)
-    base_font['sfnt'] = merge_truetype_fonts_for_pdf(*(f['sfnt'] for f in descendant_fonts))
+    base_font['sfnt'], width_for_glyph_id, height_for_glyph_id = merge_truetype_fonts_for_pdf(*(f['sfnt'] for f in descendant_fonts))
+    widths = []
+    arrays = tuple(filter(None, (f['W'] for f in descendant_fonts)))
+    if arrays:
+        for gid in all_glyph_ids_in_w_arrays(arrays):
+            widths.append(gid), widths.append(gid), widths.append(1000*width_for_glyph_id(gid))
+        base_font['W'] = merge_w_arrays((widths,))
+    arrays = tuple(filter(None, (f['W2'] for f in descendant_fonts)))
+    if arrays:
+        for gid in all_glyph_ids_in_w_arrays(arrays):
+            widths.append(gid), widths.append(gid), widths.append(1000*height_for_glyph_id(gid))
+        base_font['W2'] = merge_w_arrays((widths,))
     return t0_font, base_font, references_to_drop
 
 
diff --git a/src/calibre/utils/fonts/sfnt/container.py b/src/calibre/utils/fonts/sfnt/container.py
index bac85f17e7..394a9572ac 100644
--- a/src/calibre/utils/fonts/sfnt/container.py
+++ b/src/calibre/utils/fonts/sfnt/container.py
@@ -1,29 +1,25 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+# License: GPLv3 Copyright: 2012, Kovid Goyal <kovid at kovidgoyal.net>
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-__license__   = 'GPL v3'
-__copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
-__docformat__ = 'restructuredtext en'
-
-from struct import pack, calcsize
-from io import BytesIO
 from collections import OrderedDict
+from io import BytesIO
+from struct import calcsize, pack
 
-from calibre.utils.fonts.utils import (get_tables, checksum_of_block,
-        verify_checksums)
-from calibre.utils.fonts.sfnt import align_block, UnknownTable, max_power_of_two
-from calibre.utils.fonts.sfnt.errors import UnsupportedFont
-
-from calibre.utils.fonts.sfnt.head import (HeadTable, HorizontalHeader,
-                                           OS2Table, PostTable)
-from calibre.utils.fonts.sfnt.maxp import MaxpTable
-from calibre.utils.fonts.sfnt.loca import LocaTable
-from calibre.utils.fonts.sfnt.glyf import GlyfTable
-from calibre.utils.fonts.sfnt.cmap import CmapTable
-from calibre.utils.fonts.sfnt.kern import KernTable
-from calibre.utils.fonts.sfnt.gsub import GSUBTable
+from calibre.utils.fonts.sfnt import UnknownTable, align_block, max_power_of_two
 from calibre.utils.fonts.sfnt.cff.table import CFFTable
+from calibre.utils.fonts.sfnt.cmap import CmapTable
+from calibre.utils.fonts.sfnt.errors import UnsupportedFont
+from calibre.utils.fonts.sfnt.glyf import GlyfTable
+from calibre.utils.fonts.sfnt.gsub import GSUBTable
+from calibre.utils.fonts.sfnt.head import (
+    HeadTable, HorizontalHeader, OS2Table, PostTable
+)
+from calibre.utils.fonts.sfnt.kern import KernTable
+from calibre.utils.fonts.sfnt.loca import LocaTable
+from calibre.utils.fonts.sfnt.maxp import MaxpTable
+from calibre.utils.fonts.utils import checksum_of_block, get_tables, verify_checksums
 
 # OpenType spec: http://www.microsoft.com/typography/otspec/otff.htm
 
@@ -100,6 +96,9 @@ class Sfnt(object):
     def pop(self, key, default=None):
         return self.tables.pop(key, default)
 
+    def get(self, key, default=None):
+        return self.tables.get(key, default)
+
     def sizes(self):
         ans = OrderedDict()
         for tag in self:
diff --git a/src/calibre/utils/fonts/sfnt/head.py b/src/calibre/utils/fonts/sfnt/head.py
index 5abb0c5cf0..a9a5c69113 100644
--- a/src/calibre/utils/fonts/sfnt/head.py
+++ b/src/calibre/utils/fonts/sfnt/head.py
@@ -10,6 +10,7 @@ from struct import unpack_from, pack, calcsize
 
 from calibre.utils.fonts.sfnt import UnknownTable, DateTimeProperty, FixedProperty
 from calibre.utils.fonts.sfnt.errors import UnsupportedFont
+from calibre.utils.fonts.sfnt.loca import read_array
 from polyglot.builtins import zip
 
 
@@ -67,7 +68,7 @@ class HorizontalHeader(UnknownTable):
             'descender', 'h',
             'line_gap', 'h',
             'advance_width_max', 'H',
-            'min_left_size_bearing', 'h',
+            'min_left_side_bearing', 'h',
             'min_right_side_bearing', 'h',
             'x_max_extent', 'h',
             'caret_slope_rise', 'h',
@@ -92,12 +93,55 @@ class HorizontalHeader(UnknownTable):
         if len(raw) < 4*num:
             raise UnsupportedFont('The hmtx table has insufficient data')
         long_hor_metric = raw[:4*num]
-        fmt = '>%dH'%(2*num)
-        entries = unpack_from(fmt.encode('ascii'), long_hor_metric)
-        self.advance_widths = entries[0::2]
-        fmt = '>%dh'%(2*num)
-        entries = unpack_from(fmt.encode('ascii'), long_hor_metric)
-        self.left_side_bearings = entries[1::2]
+        a = read_array(long_hor_metric)
+        self.advance_widths = a[0::2]
+        a = read_array(long_hor_metric, 'h')
+        self.left_side_bearings = a[1::2]
+
+
+class VericalHeader(UnknownTable):
+
+    version_number = FixedProperty('_version_number')
+
+    def read_data(self, vmtx):
+        if hasattr(self, 'ascender'):
+            return
+        field_types = (
+            '_version_number' , 'l',
+            'ascender', 'h',
+            'descender', 'h',
+            'line_gap', 'h',
+            'advance_height_max', 'H',
+            'min_top_side_bearing', 'h',
+            'min_bottom_side_bearing', 'h',
+            'y_max_extent', 'h',
+            'caret_slope_rise', 'h',
+            'caret_slop_run', 'h',
+            'caret_offset', 'h',
+            'r1', 'h',
+            'r2', 'h',
+            'r3', 'h',
+            'r4', 'h',
+            'metric_data_format', 'h',
+            'number_of_v_metrics', 'H',
+        )
+
+        self._fmt = ('>%s'%(''.join(field_types[1::2]))).encode('ascii')
+        self._fields = field_types[0::2]
+
+        for f, val in zip(self._fields, unpack_from(self._fmt, self.raw)):
+            setattr(self, f, val)
+
+        raw = vmtx.raw
+        num = self.number_of_h_metrics
+        if len(raw) < 4*num:
+            raise UnsupportedFont('The vmtx table has insufficient data')
+        long_hor_metric = raw[:4*num]
+        long_hor_metric = raw[:4*num]
+        a = read_array(long_hor_metric)
+        self.advance_heights = a[0::2]
+        a = read_array(long_hor_metric, 'h')
+        self.top_side_bearings = a[1::2]
 
 
 class OS2Table(UnknownTable):
diff --git a/src/calibre/utils/fonts/sfnt/loca.py b/src/calibre/utils/fonts/sfnt/loca.py
index ff1d2e7206..04a9c37480 100644
--- a/src/calibre/utils/fonts/sfnt/loca.py
+++ b/src/calibre/utils/fonts/sfnt/loca.py
@@ -21,14 +21,18 @@ def four_byte_type_code():
             return c
 
 
+def read_array(data, fmt='H'):
+    ans = array.array(fmt, data)
+    if sys.byteorder != 'big':
+        ans.byteswap()
+    return ans
+
+
 class LocaTable(UnknownTable):
 
     def load_offsets(self, head_table, maxp_table):
         fmt = 'H' if head_table.index_to_loc_format == 0 else four_byte_type_code()
-        locs = array.array(fmt)
-        locs.fromstring(self.raw)
-        if sys.byteorder != "big":
-            locs.byteswap()
+        locs = read_array(self.raw, fmt)
         self.offset_map = locs.tolist()
         if fmt == 'H':
             self.offset_map = [2*i for i in self.offset_map]
diff --git a/src/calibre/utils/fonts/sfnt/merge.py b/src/calibre/utils/fonts/sfnt/merge.py
index 163a60f227..8c73d576ea 100644
--- a/src/calibre/utils/fonts/sfnt/merge.py
+++ b/src/calibre/utils/fonts/sfnt/merge.py
@@ -30,6 +30,26 @@ def merge_truetype_fonts_for_pdf(*fonts):
     head = ans[b'head']
     loca = ans[b'loca']
     maxp = ans[b'maxp']
+    advance_widths = advance_heights = (0,)
+    hhea = ans.get(b'hhea')
+    if hhea is not None:
+        hhea.read_data(ans[b'hmtx'])
+        advance_widths = tuple(x/head.units_per_em for x in hhea.advance_widths)
+    vhea = ans.get(b'vhea')
+    if vhea is not None:
+        vhea.read_data(ans[b'vmtx'])
+        advance_heights = tuple(x/head.units_per_em for x in hhea.advance_heights)
+
+    def width_for_glyph_id(gid):
+        if gid >= len(advance_widths):
+            gid = -1
+        return advance_widths[gid]
+
+    def height_for_glyph_id(gid):
+        if gid >= len(advance_widths):
+            gid = -1
+        return advance_heights[gid]
+
     gmap = OrderedDict()
     for glyph_id in sorted(all_glyphs):
         gmap[glyph_id] = partial(all_glyphs.__getitem__, glyph_id)
@@ -39,4 +59,4 @@ def merge_truetype_fonts_for_pdf(*fonts):
     head.update()
     maxp.num_glyphs = len(loca.offset_map) - 1
     maxp.update()
-    return ans
+    return ans, width_for_glyph_id, height_for_glyph_id