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Drywall Calculator

Sheets are the easy part. Running out of mud or tape mid-room is the usual holdup. This calculator builds the whole material list: sheets, joint compound, tape and screws, from USG's published coverage figures.

Diagram of a wall showing its length and height, with a door and a window
One wall at a time: length × height is the area every wall material covers.

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Enter your measurements

How the drywall quantities are calculated

Panel area is the wall perimeter × ceiling height, plus length × width if the ceiling is boarded too. Sheets = panel area ÷ sheet area, plus a cutting-waste allowance, rounded up. Door and window openings aren't deducted. The cut-offs around them are exactly what the waste allowance covers.

Joint compound follows USG's own data sheets for Sheetrock joint compounds: about 10 gallons per 1,000 sq ft of panels for taping and finishing coats, sold in 4.5 gal pails. Tape is geometry: with 4 × 8 sheets the layout has about 0.375 ft of joint per sq ft (~375 ft per 1,000 sq ft); 4 × 12 sheets have fewer joints per square foot (~333 ft per 1,000 sq ft). Tape is sold in 250 ft rolls. Screws follow the standard estimating rule of 1 lb of 1-1/4 in screws per 300 sq ft of board.

Painting afterwards? The Paint Calculator picks up from the same room measurements, and new drywall needs a primer coat first. Insulating the wall before the sheets go up? The Insulation Calculator counts bags or batts for the same space.

Sources

The figures behind this calculator come from published manufacturer data and industry standards:

Worked examples

12 × 12 ft room, 8 ft walls + ceiling

528 sq ft of board, 4×8 sheets, 10% waste, 5.3 gal of mud.

Buy 19 sheets + 2 pails of mud

16 × 20 ft room, 9 ft walls only

648 sq ft of board, 4×12 sheets, 10% waste, 6.5 gal of mud.

Buy 15 sheets + 2 pails of mud

10 × 10 ft room + ceiling, 8 ft walls

420 sq ft of board, 4×8 sheets, 15% waste, 4.2 gal of mud.

Buy 16 sheets + 1 pail of mud

Frequently asked questions

How many sheets of drywall do I need for a 12×12 room?
Walls and ceiling at 8 ft come to 528 sq ft. In 4×8 sheets that's 17 sheets exact, or 19 with a 10% cutting allowance, plus 2 pails (about 5.3 gal) of joint compound and a 250 ft roll of tape.
How much joint compound per sheet of drywall?
USG rates its ready-mix compounds at about 10 gallons per 1,000 sq ft of board, which works out to roughly a third of a gallon per 4×8 sheet for taping plus finishing coats. Skim-coating whole walls uses considerably more.
Should I use 4×8 or 4×12 sheets?
4×12 sheets mean fewer joints to tape and finish, so pros prefer them on long walls and ceilings, but they're heavy and awkward in stairwells and small rooms. 4×8 sheets are the DIY-friendly default.
Do I deduct doors and windows?
No. The board cut out for an opening is mostly waste anyway, and the offcuts rarely land where you need them. Standard practice estimates the full wall and lets the waste allowance absorb the openings.
How many screws are in a sheet of drywall?
Roughly 28–32 for a 4×8 sheet on 16 in framing with code spacing (12 in in the field, 8 in on edges for ceilings). By weight, the estimating rule is about 1 lb of screws per 300 sq ft of board.

Related calculators

Paint Calculator

Gallons and quarts for a room, with doors, windows and coats accounted for.

Brick Calculator

Bricks and mortar bags for a wall, by brick size.

Wallpaper Calculator

Rolls to buy, allowing for pattern repeat.

Insulation Calculator

Batts and bags for walls and attics.

Estimate disclaimer: results are planning estimates based on standard manufacturer yields and coverage figures. Site conditions, product choice and installation method change actual quantities. Verify before you buy, and follow local building code for structural work. This tool does not replace professional engineering advice.

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