Question re construction cost terms

[Julia Hwang]

Apologies first for such amateur question: in new developments, when construction companies quote construction cost for "$ X/sf", is this number usually "the total construction cost divided by living square foot ONLY" or "the totally construction cost divided by total square footage of the structure, for example, including garage (sf that are not counted when selling to buyer)"? 

Or can someone describe how the construction cost discussion usually goes in a new development? 

I was chatting with an agent who is familiar in Pomona, CA area and he told me from what he knows, the construction cost per sf is about $100-150/sf. But I couldn't figure out what this mean so would like to get some help. Thanks.