Cost to Paint a Room per Square FootSize of Room (Sq.Ft.)Average Cost to Paint Walls Only (Labor Included)Average Cost to Paint Entire Room (Labor Included)300 sq.ft. (20' x 15')$450 - $1,050$900 - $1,200400 sq.ft. (20' x 20')$600 - $1,400$1,200 - $1,600500 sq.ft. (20” x 25”)$750 - $1,750$1,500 - $2,000