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`A = 2 * L * H + 2 * W * H + L * W `
Enter a value for all fields
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: 5/8/25
- Drywall Pricing Survey Store: Menards
- Pricing for a 1/2 inch 4x8 sheet of drywall is $13.99 USD
- Pricing for a 5/8 inch 4x8 sheet of drywall is $21.38 USD
- Pricing for a 1/2 inch 4x12 sheet of drywall is $19.19 USD
- Pricing for a 5/8 inch 4x12 sheet of drywall is $24.98 USD
Room Calculators
- Volume of a Room: Computes the cubic feet (volume) of a room based on its height, length and width.
- Areas of a Room: Computes the total square feet (area) of a room based on its height, length and width. This includes the total area of the ceiling and walls for things like paint. It also individually includes the area of the ceiling, walls and floor of a room.
- Room Paint Cost: Estimates the gallons of paint needed and associated cost to paint a room based on the room dimensions, number of coats and the unit cost of paint per gallon.
- Wallpaper for a Room: Computes the number of rolls of wallpaper needed to cover the walls of a room based on the dimensions of the room and the rolls of wallpaper.
- BTUs per Hour to Heat a Room: Computes the energy (heat) required to heat a space of a certain volume by a specified temperature variance.
- Insulation Rolls for Walls of a Room:
Computes the number of rolls or batts of insulation needed for the WALLS of a room based on the length and height of the four walls. The calculator assumes standard 16" spacing on the studs. - Drywall Materials for a Room: Computes the number of drywall boards (4x8 or 4x12), number of drywall nails or screws and gallons of joint compound need for a room based on the room's dimensions.
- Ceiling Tiles for a Room: Computes the number of ceiling tiles needed to cover the ceiling of a room based on the dimensions of the room and the tiles.
- Cost of Flooring a Room: Computes the square feet of a room and then applies the price per square feet of different flooring products (e.g., hardwood, carpeting, tile)
- Room Framing Cost: Computes the number of studs and plate boards for a room and estimates the cost of framing based on the unit price of the lumber.
- Outlets and Wiring for Room: Computes the number of outlets (boxes) and length of wire to connect them in a room based on the room dimensions and the outlet spacing.
- Total Surface Area of a Room: Computes the surface area of the interior of a rectangular room including the walls, ceiling and floor based on the length, width and height of the 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