Drywall Calculator

What it calculates and who it’s for

What it estimates and who it is for

This calculator estimates drywall for one room: sheets for the walls and the ceiling, ready-mixed joint compound, paper joint tape, and screws. It’s for DIYers and remodelers hanging new board who want a shopping list before going to the store. Screw counts come from the code’s maximum screw spacing for your framing, so walls and ceilings get different counts.

How to use

Step by step

Enter the room length, width, and wall height in feet, and choose whether to include the ceiling.
Enter the door and window area to leave out, in square feet.
Pick the sheet size and framing spacing (16 in or 24 in on center).
Read the results: sheets, compound, tape, and screws, with walls and ceiling broken out.

The formula

Every variable and unit

Wall area (sq ft) = 2 × (Length + Width) × Height − Doors and windows
Ceiling area (sq ft) = Length × Width (when included)
Sheets for each surface = Area × (1 + Waste % ÷ 100) ÷ Sheet area, rounded up, where a 4×8 sheet is 32 sq ft, 4×10 is 40, and 4×12 is 48
Joint compound (gal) = Board area × 10 ÷ 1,000, rounded up (USG All Purpose ready-mixed: about 10 gal per 1,000 sq ft)
Joint tape (ft) = Board area × 370 ÷ 1,000, rounded up (USG paper joint tape: about 370 ft per 1,000 sq ft)
Screws per sheet = (Sheet length in inches ÷ Framing spacing, rounded down, + 1) × (48 ÷ Screw spacing, rounded down, + 1)
Screws = Sheets × Screws per sheet, for walls and ceiling separately

Sheets are assumed hung horizontally, so each sheet crosses the framing along its long edge and gets one row of screws on every stud or joist it crosses. Screw spacing is the maximum the IRC allows for screws without adhesive: 12 in on ceilings, 16 in on walls framed 16 in on center, and 12 in on walls framed 24 in on center.

Worked example

Real numbers, worked by hand

A 12 × 12 ft room with 8 ft walls, ceiling included, 30 sq ft of doors and windows, 4×8 sheets, studs and joists 16 in on center, 10% waste:

Walls: 2 × (12 + 12) × 8 = 384 sq ft − 30 = 354 sq ft
Ceiling: 12 × 12 = 144 sq ft
Wall sheets: 354 × 1.10 ÷ 32 = 12.17, rounded up to 13
Ceiling sheets: 144 × 1.10 ÷ 32 = 4.95, rounded up to 5 (18 sheets in all)
Compound: 498 sq ft × 10 ÷ 1,000 = 4.98, rounded up to 5 gal
Tape: 498 × 0.37 = 184.3, rounded up to 185 ft
Screws per wall sheet: (96 ÷ 16 + 1) × (48 ÷ 16 + 1) = 7 × 4 = 28; per ceiling sheet: 7 × (48 ÷ 12 + 1) = 7 × 5 = 35
Screws: 13 × 28 + 5 × 35 = 364 + 175 = 539 screws

How to read your results

Rounding and buying tips

Sheets to buy already includes the waste allowance and is rounded up for walls and ceiling separately.
Joint compound and tape are for the board area before waste, using USG’s published coverage. Coverage drops with heavy texture, more coats, or lots of outside corners.
Screws count every row on every sheet you buy. Screws are usually sold by the pound or by the box; check the count on the box you pick.

Assumptions and limits

What this estimate does not cover

The room is a rectangle with flat walls and a flat ceiling at one height. Closets, soffits, gables, and stairwells need their own areas added.
Screw spacing is the IRC maximum for gypsum board fastened with screws and no adhesive. Fire-rated assemblies, Type X board, shear walls, and diaphragm ceilings have other rules and are not covered.
Compound coverage is for USG’s ready-mixed All Purpose compound. Lightweight and setting-type compounds cover differently and aren’t estimated here.
10% waste is our estimate, not a manufacturer figure. Raise it for rooms with many openings or angled walls.
Confirm quantities with your supplier and follow the board manufacturer’s instructions and your local code.

FAQ

5 questions

How many sheets of drywall do I need for a 12x12 room?

With 8 ft walls, the ceiling, 30 sq ft of openings, and 10% waste, it’s 18 sheets of 4×8: 13 for the walls and 5 for the ceiling. The table below covers other room sizes.

How many drywall screws per 4x8 sheet?

It depends on the surface and framing. Hung across studs 16 in on center, a 4×8 wall sheet crosses 7 studs with 4 screws each at 16 in spacing, so 28. On a ceiling at 12 in spacing it’s 7 × 5 = 35. On walls framed 24 in on center, screws go at 12 in, so 5 × 5 = 25.

How much drywall mud per sheet?

USG lists about 10 gal of All Purpose ready-mixed compound per 1,000 sq ft of board, so about 0.32 gal per 4×8 sheet. A 5 gal pail covers roughly 500 sq ft, or about 15 sheets.

How much drywall tape per sheet?

About 370 ft per 1,000 sq ft of board, which is about 12 ft per 4×8 sheet.

Are bigger sheets better?

Longer sheets (4×10, 4×12) mean fewer joints to tape, which saves mud and time, but they’re heavier and harder to carry up stairs. The calculator shows how the sheet and screw counts change.

Shopping list for common room sizes

Reference

All rows use 8 ft walls, the ceiling included, 30 sq ft of doors and windows, 4×8 sheets, framing 16 in on center, and 10% waste.

Room (ft)	Wall area (sq ft)	Ceiling (sq ft)	Sheets	Compound (gal)	Tape (ft)	Screws
10 × 10	290	100	14	4	145	420
10 × 12	322	120	17	5	164	511
12 × 12	354	144	18	5	185	539
12 × 14	386	168	20	6	205	602
14 × 16	450	224	24	7	250	728

Your results

Walls

Ceiling

How screws are counted