Originally Posted by
pdlamb
It won't make much difference for warmth, but I think the right size for a tent is N+!, where N is the number of occupants.
That extra room is really useful if it rains overnight (do you want to sleep on or under your gear bag(s)?).
I largely agree. Weight and packed size differences are minimal. (150g, 1L between 1p and 2p).
One benefit of a smaller tent, though, is footprint. Easier to pitch in crowded spaces (such as some hike and bike areas) or between bushes.