Board Thread:Warhammer 40k General Discussion/@comment-91.224.27.226-20131031140001/@comment-6078851-20140109010953

i too was under the impression that the primarchs ranged between 12 - 15 feet (roughly 4 - 5 metres). they all had a strong psychic presence, whether or not they knew or admitted to it, so maybe they were all no larger than astartes and everyone thought otherwise because of their powerful aura.

emps i had at about 12 feet, and maybe an average size, bulkwise, in relation to his sons. but because of his unrivalled aura he might have been seen as 20 feet tall.

to beings who possess no psychic ability the only way to interpret such psychic aura's would be to give them a physical analogy - like height. i doubt the following idea but, it's possible emps and the primarchs were no larger than any astartes :P