These are the poverty guidelines: http://www.uscis.gov/files/form/I-864p.pdf
Household size of 2 is the smallest it goes. If someone is single, they still have to include the person they are sponsoring. I also agree with the poster above. You will need to file an I-864 affidavit of support after you are married and your husband files for adjustment of status. The I-864 is a binding contract and no one should sign it without reading and understanding exactly what they will be agreeing to when they sign it.
