Drywall Calculator
Sheets, screws, tape and joint compound — from room size, with openings deducted.
Adds 168 sq ft. Ceilings need tighter screw spacing and a second pair of hands.
4 × 8 sheets needed
19
- Wall area
- 416 sq ft
- Ceiling area
- 168 sq ft
- Openings deducted
- −51 sq ft
- Net board area
- 533 sq ft
- With 12% waste
- 597 sq ft
- 4 × 9 sheets
- 17 sheets
- 4 × 10 sheets
- 15 sheets
- 4 × 12 sheets
- 13 sheets
- Screws
- 597 — about 1.9 lb of 1¼"
- Tape
- 298 ft · 2 × 250 ft rolls
- Joint compound
- 84 lb · 2 buckets (4.5 gal)
Sheet counts are alternatives, not a combined order — pick one size. Longer board means fewer butt joints but heavier handling.
Insulating the same walls first? Use the insulation calculator →
How this is calculated
wall area = 2 × (length + width) × height ceiling = length × width net area = wall + ceiling − openings order = net area × (1 + waste%) sheets = ceil(order / sheet coverage) screws = order × 1 per sq ft (32 per 4×8 sheet) tape = order × 0.5 linear ft compound = order × 0.14 lb
Screws, tape and compound are derived from area rather than sheet count, because a 4×12 board needs the same fastening per square foot as a 4×8 — only the seam count changes. Compound assumes a standard three-coat finish; a level 5 skim adds roughly half again. Coverage figures are 32, 36, 40 and 48 square feet for 4×8, 4×9, 4×10 and 4×12 board.
Sheet sizes and coverage
| Sheet | Coverage | Half-inch weight | Best for |
|---|---|---|---|
| 4 × 8 | 32 sq ft | ~51 lb | Tight spaces, one-person work |
| 4 × 9 | 36 sq ft | ~57 lb | 9 ft walls, vertical hang |
| 4 × 10 | 40 sq ft | ~64 lb | Standard rooms, fewer seams |
| 4 × 12 | 48 sq ft | ~77 lb | Long walls, fewest butt joints |
Typical thickness by location
| Thickness | Where it goes | Notes |
|---|---|---|
| 1/4" | Curved walls, skim over old plaster | Not structural, needs backing |
| 3/8" | Repairs, remodel over existing | Uncommon in new work |
| 1/2" | Walls and most ceilings | The default |
| 5/8" Type X | Garages, party walls, ceilings | Fire rated, sags less on 24" centres |
| 1/2" mould-resistant | Bathrooms, laundry | Not a substitute for backer board in showers |
Frequently asked questions
How many sheets of drywall do I need?
Divide the total wall and ceiling area by the coverage of your sheet size — 32 square feet for 4×8, 40 for 4×10 and 48 for 4×12 — then add 10 to 15% for waste and round up. Deduct doors and windows only if they are large; small openings rarely save a whole sheet because the cutoffs are usually unusable.
Should I use 4×8 or 4×12 drywall?
Longer boards mean fewer butt joints, and butt joints are the hardest seams to hide because they are not tapered. Professionals use 12 foot board wherever it fits. The trade-off is weight and handling — a 4×12 half-inch sheet runs about 70 lb and is genuinely difficult for one person in a stairwell or a tight hallway.
How much joint compound do I need?
Plan on roughly 0.14 lb per square foot for a standard three-coat finish, so a 4.5 gallon bucket at about 62 lb covers 400 to 450 square feet. A level 5 finish with a skim coat over the whole surface can use half again as much, and hot mud for the first coat changes the mix but not the total volume by much.
Do I deduct doors and windows?
For ordering, deduct only openings larger than about 20 square feet. A standard door is around 21 square feet and a window 12 to 15, and the offcuts around them are usually too small or too awkward to reuse. Deducting every opening is the most common way people end up one sheet short on the last wall.
How many screws per sheet of drywall?
About 32 screws for a 4×8 sheet on 16 inch centres — roughly every 12 inches in the field and 8 inches along the edges. That works out near 1 lb of 1¼ inch screws per four sheets. Ceilings take more, since the code spacing is tighter and gravity is working against you.
How much drywall tape do I need?
Around half a linear foot of tape per square foot of board, so a 250 foot roll covers roughly 500 square feet. Buy more than the calculation suggests — tape is cheap, and running out mid-seam means a visible restart line that shows through paint.
Results are planning estimates. Fire-rated assemblies, ceiling framing spacing, moisture locations and fastener schedules are governed by local code — confirm the required thickness, type and screw pattern for your assembly before ordering.