20x20 Room Drywall: 36 Sheets of 4x8 (Walls + Ceiling)

Ceiling	Wall sq ft	Total sq ft	4x8 sheets	4x12 sheets
8'	640	1,040	36	24
9'	720	1,120	39	26
10'	800	1,200	42	28
12'	960	1,360	47	32

Ceiling

Wall sq ft

Total sq ft

4x8 sheets

4x12 sheets

640

1,040

720

1,120

10'

800

1,200

12'

960

1,360

Item	Walls only	Walls + ceiling
4x8 sheets	22	36
Screws (1-1/4")	640	1,040
Paper tape	237 ft	385 ft
All-purpose mud (4.5 gal)	2	3

Item

Walls only

Walls + ceiling

4x8 sheets

Screws (1-1/4")

640

1,040

Paper tape

237 ft

385 ft

All-purpose mud (4.5 gal)

How the math works

Perimeter: 2 × (20 + 20) = 80 ft
Wall area: 80 × 8 ft = 640 sq ft
Ceiling: 20 × 20 = 400 sq ft
Total × 1.10 waste = 1,144.0 sq ft
4x8 sheets: ÷ 32 = 36; 4x12 sheets: ÷ 48 = 24

Don’t subtract doors and windows on small rooms — the cut-offs rarely get reused. On big rooms subtract openings over 50 sq ft.

Trade pro tips

Hang the ceiling first, then walls top row first so the factory edge meets the ceiling.
Use 1/2" on walls; 5/8" or 1/2" ceiling board on ceilings framed 24" OC.
Stagger end joints and keep them off door and window corners.

Frequently asked questions

How many sheets of drywall for a 20x20 room?

36 sheets of 4x8 for walls and ceiling with 8' walls (22 for walls only), including 10% waste.

How many 4x12 drywall sheets for a 20x20 room?

24 sheets of 4x12 for walls and ceiling — fewer seams to tape than 36 4x8s.

How much mud and tape for a 20x20 room?

About 385 ft of paper tape and 3 × 4.5-gallon buckets of all-purpose compound for three coats.

How many drywall screws for a 20x20 room?

Roughly 1,040 1-1/4" screws (about one per sq ft at 16" OC framing) — a 5 lb box is plenty.

20x20 Room Drywall Calculator

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20x20 room by ceiling height (walls + ceiling)

Finishing materials for 20x20