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CalcBelt

Drywall calculator

Enter a room size to count the drywall (sheetrock) sheets, screws, joint compound and tape for the walls and ceiling, plus a typical installed cost.

Units
Room
Openings and sheets

Longer sheets mean fewer seams to tape.

%

10 to 15% is typical.

Many installers don't subtract doors and windows: the offcuts rarely fit anywhere else. That's why it's off by default.

Drywall needed

19 sheets

4 × 8 ft sheets for 528 sq ft, with 10% extra

For the walls
14 sheets
For the ceiling
5 sheets
Drywall screws
about 50016 in apart on walls, 12 in on ceilings
Joint compound
5.3 gal2 pails of 4.5 gal, ready-mixed
Joint tape
195 ft1 roll of 250 ft

Cost estimate

per 4 × 8 ft sheet

Sheets: $304 for 19

Typical US price $12 to $20 per 4 × 8 sheet (Home Depot, HomeGuide, October 2026). For standard 1/2 in board.

per sq ft

Hiring a pro: $1,188 (range $792 to $1,848)

Typical US price $1.50 to $3.50 per sq ft (Angi, HomeGuide, Fixr, October 2026).

How it's calculated
  1. Walls: 2 × (12 ft + 12 ft) × 8 ft = 384 sq ft; ceiling 144 sq ft
  2. Each 4 × 8 ft sheet covers 32 sq ft
  3. Walls: 384 sq ft + 10% ÷ 32 sq ft = 14 sheets; ceiling: 5 sheets (each rounded up)
  4. Screws: 875 per 1,000 sq ft on walls, 1,094 on ceilings (USG) = 494

Estimates use manufacturer data sheets and industry guides (sources). Check local codes and your supplier's figures before you order.

How to use the drywall calculator

  1. Enter the room's length, width and wall height.
  2. Leave Include the ceiling ticked if you're hanging it too.
  3. Pick the sheet size. Longer sheets mean fewer joints to tape.
  4. Leave doors and windows in unless you have large openings: offcuts rarely fit elsewhere.
  5. Read the sheets, screws, compound and tape to buy.

How to calculate drywall

Wall area = 2 × (length + width) × height
Sheets = area × (1 + waste %) ÷ sheet area

A 4 × 8 sheet covers 32 sq ft, a 4 × 10 covers 40 and a 4 × 12 covers 48. The calculator works out the walls and the ceiling separately and rounds each up, since a ceiling is usually hung with its own full sheets.

Example: a 14 × 16 ft room with 8 ft walls has 2 × 30 × 8 = 480 sq ft of wall. With 10% extra, that’s 528 sq ft, or 17 sheets of 4 × 8. The ceiling is 224 sq ft: 246 sq ft with extra, or 8 more sheets.

Supplies per 1,000 square feet

Item Amount Source
Screws, walls (16 in framing) About 875 USG
Screws, ceilings (16 in framing) About 1,094 USG
Ready-mixed joint compound About 10 gallons USG
Paper joint tape About 370 ft USG

Ready-mixed compound comes in 4.5 gallon pails, and paper tape in 250 and 500 ft rolls. Setting-type compound sold as powder covers about 1,000 sq ft per 52 lb, according to USG.

Sheet sizes

Standard drywall is 4 ft wide, and also comes 54 in wide, which covers a 9 ft wall in two rows. Lengths run from 8 to 16 ft. Longer sheets mean fewer butt joints to tape, which saves finishing time, but they’re heavier and harder to get into a room. USG’s standard panels are 1/2 in thick and its fire-rated Firecode X panels 5/8 in; check your local code for garages and other fire-rated walls.

Once the board is up, the paint calculator works out primer and paint for the same walls, and the flooring calculator or tile calculator covers the floor.

To have it hung and finished by a pro, the drywall installation cost calculator estimates the installed price for the same room.

Questions and answers

How many sheets of drywall do I need for a 12 × 12 room?

With 8 ft walls, the walls are 384 square feet: 14 sheets of 4 × 8 with 10% extra. The ceiling is 144 square feet: 5 more sheets. That's 19 sheets in total, or 13 sheets of 4 × 12.

How big are sheets of drywall?

4 ft wide and 8 to 16 ft long. USG's 1/2 in UltraLight panels come 4 ft or 54 in wide in lengths from 8 to 16 ft, and the calculator offers 4 × 8, 4 × 10, 4 × 12 and 54 in × 12 ft. A 4 × 8 sheet covers 32 sq ft and a 4 × 12 covers 48.

How many screws per sheet of drywall?

About 28 screws per 4 × 8 sheet on walls and 35 on ceilings, based on USG's tables for framing 16 in apart. The Gypsum Association's GA-216 standard spaces screws no more than 16 in apart on walls and 12 in on ceilings.

How much joint compound and tape do I need?

USG estimates about 10 gallons of ready-mixed all-purpose joint compound and about 370 feet of paper tape per 1,000 square feet of drywall. A 12 × 12 room with a ceiling (528 sq ft) needs about 5.3 gallons of compound and 195 feet of tape.

Should I subtract doors and windows?

Usually not. CertainTeed's drywall calculator says not to subtract openings. The pieces cut out of a sheet seldom fit anywhere else, so they end up as waste anyway. If you do subtract them, the calculator allows 15% waste instead of 10%.

How much does drywall installation cost?

Hanging, taping and finishing drywall typically costs $1.50 to $3.50 per square foot (Angi, HomeGuide, Fixr). A 1/2 in 4 × 8 sheet costs about $12 to $20.

How much does it cost to drywall a 12 × 12 room?

With 8 ft walls and the ceiling, a 12 × 12 ft room has 528 sq ft of board. At $1.50 to $3.50 per square foot to hang, tape and finish (HomeGuide), that is about $790 to $1,850.

How much do 20 sheets of drywall cost?

About $200 to $400, at the $10 to $20 per sheet HomeGuide gives for the board alone. Screws, joint compound and tape are extra.

How much is 1,000 sq ft of drywall installed?

About $1,500 to $3,500 at HomeGuide's $1.50 to $3.50 per square foot of board to hang, tape and finish; Angi gives $1.50 to $3.

Sources

Figures checked October 2026.