How to use the drywall calculator
Drywall, also called plasterboard or gypsum board, is bought by the sheet, but rooms are drawn in metres or feet. This calculator turns a room's dimensions into a sheet count you can order from, and adds the screws, tape and joint compound that go with it, so a fit-out budget or a material list takes a minute instead of a marked-up plan.
- Pick feet or metres and enter the room length, width and wall height.
- Choose whether to board the ceiling. For a single partition wall, enter its length as the room length and 0 as the width, then double the layers to cover both faces.
- Enter the area of openings to subtract: doors, large windows and archways. A standard door is about 21 ft² or 1.9 m².
- Choose a sheet size, the number of layers and a waste allowance. Add a price per sheet to get a board cost.
The results show the wall and ceiling areas, the net area to board, the number of sheets to buy, and rule-of-thumb quantities for screws, tape and ready-mixed joint compound.
Drywall formulas
Wall area = 2 × (Length + Width) × Height
Ceiling area = Length × Width
Net area = Wall area + Ceiling area − Openings
Sheets = ⌈ Net area × Layers × (1 + Waste) ÷ Sheet area ⌉
The sheet count is rounded up to whole sheets. Screws, tape and compound are estimated from the net boarded area: about one screw per ft², 0.37 ft of tape per ft² and 1 US gallon of compound per 100 ft². Real figures depend on the stud spacing, the joint layout and how heavily the finisher coats.
| Sheet size | Area | Typical use |
|---|---|---|
| 4 × 8 ft | 32 ft² (2.97 m²) | Standard walls up to 8 ft, easy handling |
| 4 × 10 ft | 40 ft² (3.72 m²) | 9 to 10 ft walls hung vertically |
| 4 × 12 ft | 48 ft² (4.46 m²) | Long walls and ceilings, fewer butt joints |
| 1200 × 2400 mm | 2.88 m² (31 ft²) | Standard metric board, 2.4 m ceilings |
| 1200 × 2700 mm | 3.24 m² (34.9 ft²) | 2.7 m ceiling heights |
| 1200 × 3000 mm | 3.60 m² (38.8 ft²) | Tall walls and commercial partitions |
Worked examples
A US bedroom, walls and ceiling
A 14 × 12 ft room with 8 ft walls has 2 × 26 × 8 = 416 ft² of wall and 168 ft² of ceiling. Taking off a 21 ft² door and two 12 ft² windows leaves 539 ft². With 10% waste that is 593 ft², or 19 sheets of 4 × 8 drywall, or 13 sheets of 4 × 12. Expect about 540 screws, 200 ft of tape and 5.4 gallons of compound.
A metric living room, walls only
A 5 × 4 m room with a 2.7 m ceiling has 2 × 9 × 2.7 = 48.6 m² of wall. Subtracting 4 m² of door and window leaves 44.6 m², or 49.1 m² with waste. Using 1200 × 2700 mm boards at 3.24 m² each, you need 16 sheets.
A small bedroom with the ceiling
A 4 × 4 m bedroom with 2.4 m walls has 38.4 m² of wall and 16 m² of ceiling. Less 3.5 m² of openings, the net area is 50.9 m², or 56 m² with 10% waste. In 1200 × 2400 mm boards that is 20 sheets. For an acoustic wall with two layers, set the layers to 2 and the count doubles.
Who this calculator helps
- Architects and interior designers pricing fit-outs, partitions and loft conversions while the layout is still moving.
- Estimators and quantity surveyors doing a fast board take-off before a detailed schedule.
- Drywall contractors and dryliners checking orders and delivery loads.
- Homeowners and renovators budgeting a basement finish, garage conversion or new room.
- Students learning how room geometry turns into material quantities.
Tips for drywall estimates
- Measure rooms with sloped ceilings or gables as separate shapes; the square footage calculator handles triangles and L-shapes.
- Use moisture-resistant board in bathrooms and fire-rated board where the code calls for it, and count them as separate orders.
- Hang sheets to minimise butt joints; longer boards cost more per sheet but save taping time.
- Need the paint for the finished walls? Carry the net area into the paint calculator, and check the overall budget with the construction cost calculator.
- Order a sheet or two extra for damage in transit and late changes on site.
Want to show a client the finished room before the boards go up? Try wall colours on a photo with Wall Paint.
