How much drywall do you need for a 20×20 room?

A 20×20 ft room with 8 ft walls needs 35 sheets of 4×8 drywall for the walls and ceiling (one door, one window, 10% waste), or 24 sheets of 4×12. Walls alone take 21 sheets of 4×8.

Change the numbers

The calculator below is pre-filled for this project. Adjust any value — including feet and inches — and the results update instantly.

Your results

Drywall sheets35

Total area to cover1,004 sq ft

Walls / ceiling604 / 400 sq ft

Drywall screws (≈1 per sq ft)1,120

How much drywall do you need for a 20×20 room — diagram

Drywall sheets for a 20×20 room by wall height

Walls plus ceiling, one door and one window subtracted, 10% waste.

Wall height	Area to cover	4×8 sheets	4×12 sheets
8 ft	1,004 sq ft	35	24
9 ft	1,084 sq ft	38	25
10 ft	1,164 sq ft	41	27

Breakdown

Walls: 604 sq ft after openings
Ceiling: 400 sq ft — consider 4×12 sheets or a drywall lift for the ceiling
Screws: about 1,120 (≈1 per sq ft of board)

The math

Walls 2 × (20 + 20) × 8 − 21 − 15 = 604 sq ft Ceiling 20 × 20 = 400 sq ft (604 + 400) × 1.10 ÷ 32 = 35 sheets (rounded up)

Common questions

How many sheets of drywall for a 20x20 room?

35 sheets of 4×8 for walls and ceiling with 8 ft walls, or 21 sheets for the walls only.

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

24 sheets for walls and ceiling with 8 ft walls and 10% waste.

Want the full method, tips and other sizes? See the drywall calculator guide.

Last reviewed November 1, 2026. Results are estimates — confirm with your supplier.

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