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Drywall Calculator

Calculate drywall sheets (4x8, 4x10, 4x12), joint compound mud, paper tape rolls, and drywall screws with door/window deductions.

Calculation Results

Drywall Sheet & Supply Formula

Sheets Needed = ((Wall Area + Ceiling Area - Openings) × (1 + Waste %)) / Sheet Square Footage
  • Sheet Sizes: 4x8 (32 sq ft), 4x10 (40 sq ft), 4x12 (48 sq ft). Longer sheets reduce vertical joints.
  • Joint Compound: Approximately 1.2 to 1.3 gallons per 100 sq ft for tape, fill, and finish coats.
  • Fasteners & Tape: ~5.5 lbs of 1-1/4" screws and ~370 linear feet of paper tape per 1,000 sq ft.

Step-by-Step Worked Example

Scenario: Drywalling a 20 ft × 15 ft room with 8 ft walls and ceiling, deducting 60 sq ft for doors/windows

Calculation Steps:

  1. Wall Area = 2 × (20 + 15) × 8 = 560 sq ft
  2. Ceiling Area = 20 × 15 = 300 sq ft
  3. Gross Area = 560 + 300 = 860 sq ft
  4. Net Area = 860 - 60 = 800 sq ft
  5. Area with 10% Waste = 800 × 1.10 = 880 sq ft
  6. Sheets Needed (4x8) = 880 / 32 = 28 sheets (rounded up)
  7. Drywall Mud = 800 / 100 × 1.3 = ~11 gallons (2.5 4.5-gal buckets)
Result: The room requires 28 4x8 drywall sheets ($420), 3 buckets of joint compound, 1 roll of tape, and 5 lbs of screws.

How to Use This Calculator

  1. 1Enter room dimensions or wall perimeter and height.
  2. 2Check whether the ceiling is being drywalled.
  3. 3Deduct window and door openings to avoid over-ordering.

Assumptions & Limitations

  • Estimates are based on standard national averages and current prevailing construction materials and contractor rates.
  • Actual trade bids may fluctuate according to local building code requirements, permit fees, and site topography.
  • Always obtain multiple written bids from licensed, bonded, and insured contractors before commencing work.

Frequently Asked Questions

Should I hang drywall horizontally or vertically?

Hang sheets horizontally on residential walls. Horizontal hanging creates fewer seams at eye level and ties multiple wall studs together for greater structural shear strength.

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