Drywall Calculator

≈ 20 sq ft each

≈ 15 sq ft each

%

Wall area
Ceiling area
Net area (w/ waste)
Drywall sheets (4×8)
Screws (1-lb boxes)
Joint compound

How It Works

Wall area   = 2 × (L + W) × H − doors × 20 − windows × 15
Ceiling     = L × W (if selected)
With waste   = total × (1 + waste%)
Sheets      = ceil(with waste / 32) [4×8 = 32 sq ft]
Compound    = ceil(with waste / 100) gallons

Drywall Thickness Guide

1/4 inch Double-layering over existing drywall, curved surfaces
3/8 inch Curved walls, repair patches
1/2 inch Standard walls and ceilings — most residential use
5/8 inch Fire-rated walls, garage ceilings, soundproofing

Tips

  • Buy 10% extra to account for cuts and waste. For rooms with many angles or cutouts, use 15%.
  • Hang sheets horizontally on walls (long edge parallel to floor) to minimize the number of seams and reduce butt joints, which are harder to finish.
  • Pre-mixed joint compound is easier to use. Buy a 5-gallon bucket rather than smaller containers for most rooms — it's significantly cheaper per gallon.

Frequently Asked Questions

What size drywall sheet should I use?

4×8 ft (48" × 96") is the standard and most common. Taller 4×12 sheets are used where ceilings are higher than 9 feet and can reduce butt joints. Use 4×8 for calculations in most rooms; this calculator assumes 4×8 (32 sq ft per sheet).

What thickness of drywall do I need?

1/2 inch is the standard for walls and ceilings in residential construction. 5/8 inch is used for fire-rated assemblies and garage ceilings. 3/8 inch is used for curved surfaces and over existing surfaces. 1/4 inch is only for double-layering over existing drywall.

How many screws do I need per sheet?

On walls: one screw every 16 inches along studs, roughly 32 screws per 4×8 sheet. On ceilings: one screw every 12 inches, roughly 48 screws per sheet. Screws are sold in 1-lb and 5-lb boxes — a 1-lb box holds roughly 200 screws (#6 coarse thread).

How much joint compound do I need?

As a rule of thumb, plan for about 0.5–1 gallon of pre-mixed joint compound per 100 sq ft of drywall. A 5-gallon bucket (approximately 62 lbs) covers about 500 sq ft. Three coats are typically applied: taping coat, filler coat, and finish coat.

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