Drywall Calculator

Add each wall to be drywalled. For a standard rectangular room, four walls are pre-filled.

Doors

Windows

Calculation Method

The drywall calculator estimates materials using the following steps:

1. Wall area = sum of each wall’s width × height
2. Ceiling area = ceiling length × ceiling width (if included)
3. Opening area = sum of all door and window areas (width × height × quantity)
4. Net area = (wall area + ceiling area) − opening area
5. Adjusted area = net area × (1 + waste factor)
6. Sheets = adjusted area ÷ sheet size (rounded up)

Material Estimates

Supplementary materials are estimated based on industry standards:

• Joint compound: ~0.053 gallons per sq ft of drywall (one 4.5-gallon box covers ~85 sq ft of seam area, roughly 370 sq ft of drywall for 3 coats)
• Joint tape: Approximately 1 linear foot of tape per 3.2 sq ft of drywall. Every seam and inside corner needs tape
• Drywall screws: Approximately 1 screw per sq ft of drywall, spaced 12″ on ceilings and 16″ on walls along studs 16″ on center

Common Sheet Sizes

• 4 × 8 ft (1.2 × 2.4 m) — 32 sq ft — Most common, easy to handle
• 4 × 10 ft (1.2 × 3.0 m) — 40 sq ft — Fewer seams on taller walls
• 4 × 12 ft (1.2 × 3.7 m) — 48 sq ft — Best for wide walls, reduces joints

Tips

• Use 10% waste for simple rectangular rooms and 15–20% for rooms with many corners, soffits, or angles
• Hang sheets horizontally on walls to reduce the number of seams
• Use 5/8″ drywall for ceilings to resist sagging, and 1/2″ for walls
• For fire-rated walls (garage to house), use Type X 5/8″ drywall
• Buy screws in bulk—a 5 lb box of 1-1/4″ screws holds roughly 700 screws