MiniCalci

Calculators & Converters
Construction & DIY

Drywall Calculator

Free drywall calculator for 4x8 and 4x12 sheet counts, joint compound (mud in gallons), drywall screws, and tape. Includes wall and ceiling dimensions with door/window deductions.

~21 sq ft per door

~15 sq ft per window

What Does This Drywall Calculator Do?

Whether finishing a basement, garage, bedroom, or drywalling an entire new addition, this drywall calculator computes the complete bill of materials for your drywall project. It determines the number of 4×8 or 4×12 gypsum wallboard sheets, joint compound (mud) buckets, drywall screws, and paper or mesh joint tape rolls needed.

The Drywall Calculation Formula

  • Wall Area = 2 × (Room Length + Room Width) × Ceiling Height
  • Ceiling Area = Room Length × Room Width
  • Net Surface Area = (Wall Area + Ceiling Area) - (Door & Window Openings)
  • Sheets (4×8) = (Net Surface Area × 1.10) / 32
  • Sheets (4×12) = (Net Surface Area × 1.10) / 48

Worked Example: 16 ft × 12 ft Room with 8 ft Ceiling

  1. Wall Area: 2 × (16 + 12) × 8 = 448 sq ft.
  2. Ceiling Area: 16 × 12 = 192 sq ft.
  3. Gross Total: 448 + 192 = 640 sq ft.
  4. Deductions (2 doors, 2 windows): ~72 sq ft → Net = 568 sq ft.
  5. With 10% Waste: 568 × 1.10 = 625 sq ft.
  6. Materials Needed: 20 sheets of 4×8, ~4 buckets of joint compound, ~5 lbs of screws, and 2 rolls of tape.

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Frequently Asked Questions

How many drywall sheets do I need for a 12x12 room?
For a 12×12 room with 8-foot ceilings including the ceiling: Wall area is 2 × (12 + 12) × 8 = 384 sq ft. Ceiling area is 144 sq ft. Total gross area is 528 sq ft. Subtracting 2 doors and 1 window (~57 sq ft) leaves 471 net sq ft. With a 10% waste factor (518 sq ft), you need **17 sheets of 4×8 drywall** (or **11 sheets of 4×12 drywall**).
Is 4x8 or 4x12 drywall better for DIYers?
4×8 sheets (32 sq ft, ~50 lbs) are much easier to transport in a pickup or SUV and can be lifted and positioned by a single person. 4×12 sheets (48 sq ft, ~75 lbs) create 25% fewer seams and tapered joints for a smoother finish, but require two people or a drywall hoist.
How much drywall mud (joint compound) do I need?
A standard guideline is approximately 0.053 gallons of ready-mixed joint compound per square foot of drywall (covering taping, fill, and skim coats). That equates to about **one 4.5-gallon bucket for every 80–100 square feet of surface area** or roughly 1 bucket per 3 sheets of 4×8.
How many drywall screws per sheet?
Building codes typically require screws spaced every 12 inches on ceilings and every 16 inches on wall studs. That equals approximately **32 to 36 screws per 4×8 sheet** (about 1 to 1.5 lbs of 1-1/4" coarse drywall screws per 5 sheets).

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How this is calculated: This tool uses standard, well-established formulas for construction & diy calculations. Results are estimates for informational and planning purposes — always double-check figures for anything with real-world consequences (e.g. ordering materials or submitting grades).