a few things to consider...
If you are referring to the square footage of your home, you must advertise it as accurate to the best of your knowledge. The county assessor is one source, as is an appraiser. You may also measure it yourself to the standards of the above mentioned. Realtors use specifice disclosures prepared by attorneys for the state to disclose the pertinent information about yoru home....and portray it as accurate.
Bedrooms must be conforming to count them. Basements that are professionally finished have permits with the county so they can accuratley assess the taxes on your home. A few examples of challenges to evaluate
You may wish to meet with an appraiser of the assessors office to discuss the particulars of your home.
The sale of your home gets even more complicated. You may wish to hire the services of a Realtor.
Best of luck,
Keller Williams Realty Success