As we're striving to get an idea how our creatures relate in sizes, here's a list we agreed upon in the media team. We should be able to tweak that a little as needed. We don't have manu non-human models yet.

                size in meters      size relative to humans
species         male    female          male    female

seethra         2,5     2,5             145%    145%
troll           2,2     2,2             130%    130%
ogre            2,1     2,0             125%    120%
eriphiad        1,8     1,8             105%    105%
sauten          1,8     1,8             105%    105%
dipvira         1,7     1,7             100%    100%
khatinid        1,7     1,7             100%    100%
human           1,7     1,6             100%    95%
half-orc        1,7     1,6             100%    95%
orc             1,6     1,6             95%     95%
half-elf        1,5     1,5             90%     90%
elf             1,4     1,5             80%     90%
goblin          1,3     1,1             75%     65%
dwarf           1,0     1,0             60%     60%
faerie          0,4     0,4             25%     25%
pixie           0,2     0,2             10%     10%
I guess it could need some more work, but it's a start.
Thanks to Siri Austvik for compiling this list.