Drywall Calculator

Estimate drywall sheets, joint compound, and tape for walls and ceilings. Includes waste allowance.

Room Dimensions (Feet)

Length (ft)

Width (ft)

Wall Height (ft)

Panel Sheet Sizing

Waste Allowance (%)

Include Ceiling

Drywall & Finishing Materials

SPEC_VERIFIED

Drywall Sheets Needed (4x8)

25sheets

Detailed Material Breakdown

Total Surface Area: 704 sq ft
Estimated Joint Tape: 291 linear feet
Estimated Ready-Mix Compound: 41.82 gallons
Estimated Fasteners: 775 drywall screws

Calculation Formula & Assumptions

Calculates the number of 4×8 or 4×12 drywall panels required for walls and ceilings, along with estimated joint compound, paper tape, and screws.

Sheets = ⌈Total Area ÷ Sheet Area × (1 + Waste %)⌉

Step-by-step breakdown:

Calculate wall area: Perimeter × Wall Height
Calculate ceiling area: Length × Width (if included)
Total Area = Wall Area + Ceiling Area
Divide total area by sheet coverage (32 sq ft for 4×8; 48 sq ft for 4×12)
Add 10%–15% waste allowance.
Estimate tape, joint compound, and fasteners based on total square footage.

Note: Using 4×12 sheets reduces the number of difficult recessed butt joints by up to 25%.

Worked Calculation Example

Basement Room (14×16 ft, 8 ft ceiling)

Drywalling walls and ceiling of a 14×16 ft room using 4×8 sheets.

Room:14 ft × 16 ft × 8 ft high

Ceiling:Included

Sheet Size:4×8 ft (32 sq ft)

Waste Factor:10%

Calculation Steps:

Wall Area = 2 × (14 + 16) × 8 = 480 sq ft
Ceiling Area = 14 × 16 = 224 sq ft
Total Area = 480 + 224 = 704 sq ft
With 10% waste: 704 × 1.10 = 774.4 sq ft
Sheets (4×8) = 774.4 ÷ 32 = 24.2 => 25 sheets
Joint Tape = ~280 linear feet; Joint Compound = ~7 gallons; Screws = ~750

Order 25 sheets of 4×8 drywall, 1 roll of 300' tape, two 4.5-gallon buckets of mud, and 1 box of screws.

How to Use This Calculator

Enter room length, width, and ceiling height.
Choose whether to include the ceiling.
Select sheet size (4×8 ft or 4×12 ft).
Set waste allowance (10% standard; 15% for rooms with many closets/angles).

Common Estimation Mistakes to Avoid

Subtracting windows and doors too aggressively (cutouts still produce scrap that cannot be reused).
Using 1/2" drywall on 24" on-center ceiling framing (which can sag; use 5/8" or ceiling board).

Frequently Asked Questions

Budget approximately 0.05 gallons (or roughly 5 lbs) of ready-mix joint compound per square foot of drywall installed across 3 coats.

In the United Kingdom, drywall is known as plasterboard (or wallboard). Standard UK plasterboard sheets measure 2400 mm × 1200 mm (equivalent to an 8×4 foot sheet in North America) and 12.5 mm in thickness.

In residential wood-framed construction, hanging drywall sheets horizontally (perpendicular to wall studs) is industry standard because it produces fewer total linear feet of seams and bridges framing imperfections.