Drywall Calculator

About This Calculator

Enter room dimensions, ceiling height, and the number of door and window openings, then see exactly how many drywall sheets to order — always rounded up — plus a joint compound estimate based on the net wall area.

How It Works

Wall area = 2 × ceiling height × (length + width). Net area = wall area − door openings (≈20 sq ft each) − window openings (≈12 sq ft each). Sheets = ⌈net area ÷ sheet area⌉ (32 sq ft for 4×8; 48 sq ft for 4×12). Joint compound ≈ 0.053 lb/sq ft of net wall area (USG estimating rule of thumb).

The Formula

Frequently Asked Questions

Should I choose 4×8 or 4×12 sheets?

4×8 sheets are easier to handle solo and are the standard for most rooms. 4×12 sheets create fewer seams on long walls (fewer butt joints to tape and finish), which is popular for professional installations in rooms with 9–10 ft ceilings. They require two people to carry and hang safely.

Does this account for ceiling drywall?

No — this calculator covers walls only. For ceilings, multiply room length × width to get ceiling area, then divide by your sheet area and round up separately.

How accurate is the joint compound estimate?

The 0.053 lb/sq ft figure is a US Gypsum (USG) rule of thumb for a standard 3-coat system (tape, topping, skim). Actual usage varies with applicator skill, board gaps, and whether you add a texture coat. Add a 10–15% buffer to your order.

Are door and window cutouts exact?

The calculator deducts approximately 20 sq ft per door and 12 sq ft per window — industry-standard averages. Your actual openings may differ. For precise takeoffs on large projects, measure each opening individually and enter the total deduction as additional "doors" or use the net area directly.