A 12’ x 13’ room with a presumed 8’ height (not including windows and doors) would require a minimum 2 gallons to cover in two coats, with a spread rate of 350-400 sq ft per gallon. Typically rooms such as bedrooms, offices, and family spaces use an Eggshell with a subtle luster, or Matte which is a washable flat enamel, with Semi-Gloss reserved for trim work and doors. If you desire a higher sheen for the walls, Satin is a good choice, very durable and easy to clean. We have sheen charts in our color showroom to better display their differences to help in your decision.