How much seer do you need for a 1400 sq ft home?

I think you mean how much BTU or tons you need. SEER is a rating regarding the efficiency of the A/C unit. The tonnage you require is dependent on some things like your climate and amount of Windows, etc. A rule of thumb, that I believe is slightly over sized, is 6000 BTU for each 250 square feet. This puts you at about a 3 ton unit. For a 1400 square foot home that should be quite sufficient in most climates. If you live in a mild climate and/or have a very thermally efficient home, you could reduce to a 2.5 ton, but you wouldn't save a lot on the installation.