Mercedes say they cannot be precise about how many elements of his power unit will be changed, at least until they have firmed up plans on Friday.
Both the team and Hamilton have been aware of looming penalties given he had used the maximum five permitted MGU-H and turbo components before the summer break.
"As far as I am aware we will be taking a penalty here this weekend, yes" Hamilton said in the pre-weekend press conference. "I have no engines left."
Asked where he could hope to finish as a result, Hamilton added: "I'll do everything I can to minimise the impact it will have.
"Beyond that penalty, I think I'll be able to continue with the momentum I had before the break."
Hamilton carries a 19-point lead over Nico Rosberg into Spa, the Briton having won six of the last seven races in the build up to the summer break.