The Room Surface Area calculator computes the surface area of the interior of a rectangular room including the walls and ceiling based on the length, width and height of the room. 
INSTRUCTIONS: Choose units and enter the following:
- (L) Length of Room
- (W) Width of Room
- (H) Height of Room
Room Surface Area (A): The calculator will return the total surface area (A) of the interior room including the walls and ceiling in square feet. However, this can be automatically converted to other area units (e.g. square meters) via the pull-down menu.
The Math / Science
The surface area of the interior of a room including the walls and ceiling is the sum of the area of the walls and the area of the ceiling. These areas can be determined by the dimensions of the room. The total area is the sum of:
- The area of two walls, where Area = L*H
- The area of two walls, where Area = W*H
- The area of the ceiling, where Area = L*W
This totals to compute the area of the interior of the room in the following equation:
A = 2(L•H) + 2(W•H) + L•W
where:
- A = Total Surface Area of a Room including walls and ceiling
- L = Length of the room
- W = Width of the room
- H = Height of the room
Note: The above does not include the area of the floor.
Drywall Pricing
Pricing for drywall is an estimate. The pricing per sheet used in this estimator is as follows:
- Drywall Pricing Survey Date: 3/28/23
- Drywall Pricing Survey Store: Menards
- Pricing for a 1/2 inch 4x8 sheet of drywall is $10.67 USD
- Pricing for a 5/8 inch 4x8 sheet of drywall is $17.78 USD
- Pricing for a 1/2 inch 4x12 sheet of drywall is $17.78 USD
- Pricing for a 5/8 inch 4x12 sheet of drywall is $21.16 USD
Room Calculators
- Number of gallons to paint or primer a room.
- Cost to paint or prime a room.
- Surface area of the interior walls of a room
- Surface area of the interior walls and ceiling of a room.
- Floor area of a room
- Volume of a room
- Energy (BTUs/hr) needed to heat a room
- Insulation for a Room
- Number of Studs in a Room
- Number of drywall sheets needed for a room
- Cost of studs needed to frame a room
Building Calculators
- Area of a Roof
- Pitch of a Roof
- Number of Trusses Needed for a Roof
- 4x8s needed for a roof
- Shingles needed for a roof
- Number and Length of Metal Roof Panels
- Number and Length of Purlins
- Number and Length of Rafters
- Number and Length of Rafter and Collar ties
- Number and Length of wall top and bottom wall plates
- Number of Studs for a Room
- Number of Studs in a Wall
- Room Interior Area (wall and ceiling)
- Cubic Feet in a Room (volume)
- Number of 4x8 or 4x12 Sheets for a Room
- Number and Length of Floor Joists
- Number of Joist Hangers
- Compute the Cost of Floor Joists
- Compute iJoists for larger floors
- Compute the Number of 4x8 Sheets to cover the Deck or Floor
- Compute the number of Decking Boards to cover the deck or floor
- Surface Area of the Room including the walls and ceiling
- Drywall to Cover a Room including the walls and ceilings
- Drywall cost of Material (wall board) for a room including the walls and ceiling
- Cost to Finish Drywall. This includes taping, mudding and sanding up to preparation to paint.
- Drywall Sheets for a Wall or Area
- Drywall Cost of Material (wall boards) for a Wall
- Compute the number of gallons to paint or primer a room
- Compute the cost to paint or prime a room
- Compute the volume of a room
- Compute the surface area of the interior walls of a room
- Compute the floor area of a room