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 for 4×8, 40 for 4×10, 48 for 4×12) and round up. For a 12 × 14 × 8 ft (3.6 × 4.2 × 2.4 m) room with ceiling, 1 door, and 1 window: 416 + 168 − 36 = 548 sq ft × 1.10 = 603 → 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 per door (3 × 7 ft typical) and 15 sq ft per window (3 × 5 ft 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, 4×12 = 48 sq ft. 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, suitable for textured surfaces (orange peel, knockdown) — coverage rate 0.040 lb/sq ft. Level 4: standard paint-ready for most residential walls (smooth, no texture) — 0.130 lb/sq ft. 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. 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. Level 4 (paint-ready, most residential): 0.130 lb/sq ft. Level 5 (glossy/critical lighting): 0.180 lb/sq ft. For 500 sq ft (46 m²) at Level 4: 65 lb / 5.4 gal — about two 5-gallon buckets. Convert pounds to gallons by dividing by 12 (USG Sheetrock density). Use the dedicated Drywall Mud Calculator for finer control or direct-area input.

Industry standard is 1 screw per square foot of drywall, which works out to ~32 screws per 4×8 sheet (32 sq ft). 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 of thumb satisfies that pattern. The calculator gives the total screw count directly. 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 for a 12 × 14 ft / 3.6 × 4.2 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) is the residential default — easy to handle solo, fits standard truck beds, and is stocked at every big-box. 4×10 (40 sq ft) reduces horizontal seams on 9-10 ft walls and 8-ft walls hung horizontally. 4×12 (48 sq ft) is best for pro crews on tall walls (10-12 ft cathedral ceilings) — fewer seams means 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, 4×12 = ~75 lb.

Yes — pick Metric in the unit selector at the top and inputs switch to meters and m². Sheet sizes display 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) — the 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 = 3.6 × 4.2 × 2.4 m. Your unit choice persists across pages and tabs via localStorage.