Building / DIY

Drywall Calculator: Sheets, Screws, Tape & Mud

This drywall calculator estimates 4×8, 4×10, or 4×12 sheets from wall and ceiling area minus openings, then adds waste plus rough screws, tape, and joint compound.

Room length (ft)

Long wall of a rectangular room.

Room width (ft)

Ceiling height (ft)

Used for all four walls.

Include the ceiling. Area is length times width.

Opening 1

Width (ft)

A standard door is about 3 ft by 7 ft.

Height (ft)

Opening 2

Width (ft)

Height (ft)

Sheet size

4×8 is 32 sq ft, 4×10 is 40, and 4×12 is 48.

Waste (%)

10–15% is typical for cuts around openings and corners.

Drywall estimate

4×8 sheets: 16
Screws: 469
Tape rolls (162.43 ft): 1
Mud buckets (4.39 gal): 1
Net area: 439 sq ft
Area with waste: 482.9 sq ft

Walls: 2 × (12 + 10) × 8 = 352 sq ft. Ceiling: 12 × 10 = 120 sq ft. Openings: 3 × 7 + 3 × 4 = 33 sq ft. Net area: 352 − 33 + 120 = 439 sq ft. With 10% waste: 482.9 sq ft. A 4×8 sheet is 32 sq ft, so 482.9 ÷ 32 = 15.091, which rounds up to 16 sheets. Screws: 319 × 1 + 120 × 1.25 = 469. Tape: 439 × 0.37 = 162.43 ft (1 roll of 500 ft). Joint compound: 439 ÷ 100 = 4.39 gal (1 bucket of 4.5 gal).

Screws, tape, and joint compound are rough allowances. Framing spacing, finish level, and the product label change the real amounts.

How to use

Enter the room length, width, and ceiling height in feet.
Leave Include ceiling on, or turn it off for walls only.
Add doors and windows. A blank row is skipped. Large openings are subtracted from the walls.
Choose a 4×8, 4×10, or 4×12 sheet and a waste percent. 10% or 15% is typical.
Read the sheets to buy, screws, tape, and joint compound. The product label wins on coverage.

Formula

Wall area = 2 × (length + width) × height. Ceiling area = length × width when a ceiling is included. Net area = wall area − openings + ceiling area. Sheets = net area × (1 + waste% / 100) ÷ sheet area, rounded up. A 4×8 sheet is 32 sq ft, a 4×10 is 40, and a 4×12 is 48. Screws are about 1 per sq ft of wall and 1.25 per sq ft of ceiling. Tape is about 0.37 ft per sq ft (370 ft per 1,000), sold in 500 ft rolls. Joint compound is about 1 gallon per 100 sq ft, in 4.5 gallon buckets.

Example. A 12 × 10 ft room with 8 ft ceilings, a 3 × 7 door, and a 3 × 4 window has 352 sq ft of wall and 120 sq ft of ceiling. Net area is 439 sq ft. With 10% waste that is 482.9 sq ft, which is 16 sheets of 4×8. Screws: 469. Tape: 162.43 ft (1 roll). Joint compound: 4.39 gal (1 bucket of 4.5 gal).

Example. The same room with 4×12 sheets (48 sq ft) needs 11 sheets. 4×10 sheets (40 sq ft) need 13.

Check the bucket

Screw spacing, tape, and joint compound depend on framing, how the sheets are hung, and the finish level. The counts here are rough allowances so you can plan a store run. Read the coverage on the screw box, the tape, and the compound bucket before you buy.

Frequently asked questions

How many sheets of drywall do I need?

Divide the total wall and ceiling area by the sheet area (32 sq ft for 4x8, 48 sq ft for 4x12), then add waste.

How much waste should I add?

About 10-15% is typical for cuts around openings and corners.

Do I subtract doors and windows?

Yes for large openings. Many pros skip small ones because the cutouts are rarely usable.

Should I use 4x8 or 4x12 sheets?

Larger sheets mean fewer seams to tape but are heavier to handle. 4x8 is easier for DIY.

How much joint compound do I need?

It depends on the product and finish level. The tool gives an estimate; check the coverage on the bucket.