Drywall / Sheetrock Calculator (Sheets, Mud, Screws)
Estimate drywall, plasterboard, or sheetrock sheets plus joint compound, tape, and screws for a room from its length, width, and ceiling height.
Board area: gross 54.5 m² → ordered 52.8 m² (walls 40.5 m² + ceiling 14.0 m²). Compound ≈ 34 kg for a 3-coat finish.
How this works
Board area is the wall perimeter times the height, plus the ceiling if included, minus an openings deduction, plus waste:
wall area = 2 × (L + W) × H
ceiling = include? L × W : 0
net = (wall + ceiling) × (1 − openings%)
ordered = net × (1 + waste%)
sheets = ceil(ordered / sheet area)Consumables use typical figures: ~32 screws per sheet, ~1.2 m of tape and ~0.65 kg of joint compound per m² of board (one 28 kg bucket per ~43 m²).
Worked example
A 4 m × 3.5 m room with a 2.7 m ceiling, walls + ceiling, 12% openings, 10% waste, 4×8 ft sheets:
- walls =
2 × 7.5 × 2.7= 40.5 m²; ceiling =14m² → gross 54.5 m² - net =
54.5 × 0.88≈ 47.96 m²; ordered =× 1.10≈ 52.8 m² - sheets =
ceil(52.8 / 2.973)= 18; screws ≈ 576; compound ≈ 2 buckets
Sources
- Consumable rules of thumb from USG / gypsum board fixing and finishing guides; confirm screw spacing against local code.
FAQ
How do I calculate how many drywall sheets I need?
Add up the wall area (twice the room perimeter multiplied by the ceiling height) and, if you are boarding the ceiling too, the floor area. Deduct a percentage for doors and windows, add a waste allowance, then divide by the area of one sheet and round up. A 4×8 ft sheet is 32 ft² (about 2.97 m²); a 1200×2400 mm sheet is 2.88 m². This calculator does all of that and also estimates screws, tape, and joint compound.
What size drywall sheet should I use?
Longer sheets mean fewer joints to tape and a flatter finish, so 4×12 ft (or 1200×3000 mm) sheets are popular with professionals when access allows. For DIY work in tight stairwells or small rooms, 4×8 ft (1200×2400 mm) sheets are far easier to carry and lift. Ceilings are usually done with the longest sheet that two people can safely hold overhead. Thickness — typically 12.5 mm (1/2 in) for walls and 15 mm (5/8 in) for ceilings or fire-rated assemblies — does not change the sheet count, only the product you buy.
How much joint compound and tape do I need?
As a rough guide, budget about 0.65 kg of all-purpose joint compound per square metre of board for a standard three-coat finish, which is roughly one 28 kg (4.5-gallon) bucket per 43 m² of drywall. For tape, allow about 1.2 metres of paper or mesh tape per square metre of board. Level 5 finishes, skim coats, and textured finishes use noticeably more compound, so treat these figures as a starting point.
How many screws does a sheet of drywall need?
A common rule is about 32 screws per sheet: screws every 300 mm (12 in) in the field and every 200 mm (8 in) along the edges when fixing to framing at 400 mm (16 in) centres. Ceilings and fire-rated board may call for closer spacing, which raises the count. This calculator uses roughly 32 screws per sheet; check your local code or the board manufacturer's fixing schedule for the exact pattern.
Should I deduct doors and windows?
For a small room with one door you can often ignore openings and let the waste allowance absorb them. For rooms with large windows, sliding doors, or multiple openings, deducting 10 to 15 percent of the gross area gives a more accurate sheet count and avoids over-buying. Enter that figure in the openings field. Remember that you still need board around openings, so never deduct the full opening area if you are cutting sheets to fit.
Is drywall the same as plasterboard and sheetrock?
Yes — they are regional names for the same product: a gypsum core wrapped in paper (or sometimes fibreglass) facing. 'Drywall' and 'Sheetrock' (a brand name) are common in the United States and Canada, while 'plasterboard' is used in the UK, Australia, and much of Asia. The calculation is identical; only the standard sheet sizes and thicknesses differ by region, which is why this tool lets you pick both imperial and metric sheet sizes.