Drywall Calculator

Total drywall area = wall area + ceiling area − openings. Wall area = 2 × (length + width) × height. Ceiling area = length × width when included. Subtract 21 sq ft (1.95 m²) per door and 15 sq ft (1.39 m²) per window. Multiply by 1.10 to add 10% waste, then divide by sheet area (32 sq ft / 2.97 m² for 4×8, 40 sq ft / 3.72 m² for 4×10, 48 sq ft / 4.46 m² for 4×12) and round up. For a 12 × 14 × 8 ft (3.66 m × 4.27 m × 2.44 m) room with ceiling, 1 door, and 1 window: 416 + 168 − 36 = 548 sq ft (50.9 m²) × 1.10 = 603 sq ft (56.0 m²) → 19 sheets of 4×8.

Sum every wall surface plus the ceiling, then subtract openings. For a rectangular room: walls = 2 × (length + width) × height, ceiling = length × width when included. Subtract a standard 21 sq ft (1.95 m²) per door (3 × 7 ft / 0.9 × 2.1 m typical) and 15 sq ft (1.39 m²) per window (3 × 5 ft / 0.9 × 1.5 m average). The calculator above does this automatically. You just enter dimensions and door/window counts.

Divide your total drywall area (after waste) by the sheet area and round up. 4×8 sheet = 32 sq ft (2.97 m²), 4×10 = 40 sq ft (3.72 m²), 4×12 = 48 sq ft (4.46 m²). A 500 sq ft (46 m²) job needs 16 sheets of 4×8, 13 of 4×10, or 11 of 4×12 with 0% waste. Add 10-15% for cuts around openings and corners. The reference table on this page gives the full grid by sheet size and area.

These are USG joint-finish standards. Level 3: tape and three coats of mud, for textured surfaces (orange peel, knockdown). Coverage rate 0.040 lb/sq ft (0.20 kg/m²). Level 4: standard paint-ready for most residential walls (smooth, no texture). 0.130 lb/sq ft (0.63 kg/m²). Level 5: skim coat over the entire surface plus three coats. Required for glossy paint or critical lighting (gallery walls, large windows). 0.180 lb/sq ft (0.88 kg/m²). Higher levels need more mud and more labor.

Multiply drywall area by the finish-level rate. Level 3 (texture-ready): 0.040 lb/sq ft (0.20 kg/m²). Level 4 (paint-ready, most residential): 0.130 lb/sq ft (0.63 kg/m²). Level 5 (glossy/critical lighting): 0.180 lb/sq ft (0.88 kg/m²). For 500 sq ft (46 m²) at Level 4: 65 lb (29.5 kg) / 5.4 gal (20.4 L), about two 5-gallon buckets. Convert pounds to gallons by dividing by 12 (USG Sheetrock density). Use the Drywall Mud Calculator for finer control or direct-area input.

Industry standard is 1 screw per square foot of drywall (~11 per m²), which works out to ~32 screws per 4×8 sheet (32 sq ft / 2.97 m²). IRC R702.3.5 specifies maximum 16 in (40 cm) on-center for ceilings and 8 in (20 cm) along sheet edges. The 1-screw-per-sq-ft rule satisfies that pattern. The calculator gives the total screw count. Buy 25% extra. You'll bend or strip a few.

10% is standard for typical residential rooms with simple geometry. Bump to 15-20% for rooms with many openings (bathrooms with windows, kitchens with cabinets), angled walls (vaulted ceilings, dormers), or first-time DIYers. Waste covers the offcuts you can't reuse: small triangles around windows, the strips between studs and corners. Mud, tape, and screws scale on the actual finished surface, not waste, so waste % only affects sheet count.

Yes for a full room finish. The ceiling adds length × width of drywall (168 sq ft / 15.6 m² for a 12 × 14 ft / 3.66 m × 4.27 m room). For wall-only projects (basement partition walls, garage retrofits, accent walls), toggle the ceiling off. The calculator's Include Ceiling switch handles both cases. If your ceiling is already finished or you're using a different material (drop ceiling, tongue-and-groove planks), exclude it.

4×8 ft (1.2 × 2.4 m, 32 sq ft / 2.97 m²) is the residential default. Easy to handle solo, fits standard truck beds, stocked at every big-box. 4×10 (40 sq ft / 3.72 m²) reduces horizontal seams on 9-10 ft (2.7-3.0 m) walls and on 8-ft (2.4 m) walls hung horizontally. 4×12 (48 sq ft / 4.46 m²) is best for pro crews on tall walls (10-12 ft / 3.0-3.7 m cathedral ceilings). Fewer seams mean less mud and less labor, but the panels need two people and won't fit in a small truck. Sheet weight: 4×8 = ~50 lb (23 kg), 4×12 = ~75 lb (34 kg).

Yes. Pick Metric in the unit selector at the top and inputs switch to meters and m². Sheet sizes show metric labels (1.2 × 2.4 m for 4×8, 1.2 × 3.0 m for 4×10, 1.2 × 3.7 m for 4×12). Actual sheets sold in metric markets are sized close to these. Mud weight outputs in kg. Gallons stay in gallons (joint compound is sold by the gallon globally). Common conversions: 12 × 14 × 8 ft room = 3.66 m × 4.27 m × 2.44 m. Your unit choice sticks across pages and tabs via localStorage.