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QuantoObra

Drywall Calculator

Calculate drywall (plasterboard) sheets for walls and ceilings, plus the screws, joint compound and tape to finish them.

Results update as you type.

Room

Measure by
ft
ft
ft

Deducts 3' × 6'8" each

Deducts 3' × 4' each

Sheets & materials

%

10–15% typical

$

Drywall sheets

18sheets

Board area
496 ft²
32 ft² openings deducted
Walls / ceiling
13 / 5
sheets
Screws
546
1.7 lb
Compound / tape
2 / 1
buckets / rolls

Shopping list

  • 184' × 8' drywall sheets

    13 walls + 5 ceiling

  • 1.7 lb1-1/4" coarse drywall screws

    ≈ 546 screws

  • 24.5 gal bucket (~62 lb) all-purpose joint compound

    68 lb for 3 coats

  • 1500 ft roll paper joint tape

    183 ft of joints

  • —Corner bead for outside corners

    Measure outside corners

Add prices below to see a cost estimate.

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How we calculate

walls = 2 × (length + width) × height − doors − windows
ceiling = length × width
sheets = ⌈walls × (1 + waste %) ÷ sheet area⌉ + ⌈ceiling × (1 + waste %) ÷ sheet area⌉
screws ≈ 1 per ft² (10.8 per m²) · compound ≈ 0.138 lb/ft² (0.67 kg/m²) · tape ≈ 0.37 ft per ft² (1.2 m/m²)

Accessory rates are industry rules of thumb (USG / Gypsum Association) for a level 4 finish. Doors are deducted at 3 × 6'8" (0.9 × 2.1 m) and windows at 3 × 4 ft (1.2 × 1.2 m).

Which drywall thickness?

UseThickness
Standard interior walls1/2 in (12.5 mm)
Ceilings, 24 in joist spacing1/2 in sag-resistant or 5/8 in
Fire-rated (garage/house wall)5/8 in Type X (15 mm)
Bathrooms (not in showers)1/2 in moisture-resistant

Hang ceilings first, then walls with sheets running horizontally — it reduces the length of joints at eye level and ties the studs together.

Frequently asked questions

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

With 8 ft walls: 384 ft² of wall ÷ 32 ft² per 4×8 sheet = 12 sheets, plus 10% waste = 14 sheets (fewer after deducting doors and windows). The 144 ft² ceiling needs another 5 sheets.

Should I use 4x8 or 4x12 drywall?

4×12 sheets cover a 12 ft wall in one piece, so there are fewer butt joints to tape. They’re heavy (≈ 80 lb for 1/2 in) and need two people. 4×8 sheets are easier to carry and fit in most vehicles.

How many screws per sheet of drywall?

About 32 screws per 4×8 sheet — roughly one per square foot — with studs at 16 in centres, screws 12 in apart on walls and 8 in on ceilings.

How much joint compound do I need?

Plan on roughly 0.14 lb per ft² of board for a three-coat finish — about one 4.5-gallon bucket per 450 ft². Setting-type compound for the first coat reduces shrinkage.

Do I subtract doors and windows for drywall?

Pros often only deduct large openings because cut-outs become offcuts anyway. Deducting standard doors and windows is fine when you plan sheet layout carefully; keep 10–15% waste.

Related calculators

Paint for walls & ceiling →

Next step: primer and paint for your new drywall.

How many sheets of drywall do I need? →

Sheets, screws, compound and tape for walls and ceilings, with a worked room example.

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