Drywall calculator
Enter the room's size, wall height and openings to get the number of drywall sheets, plus joint compound and tape from USG's published coverage. The defaults are a 12 × 12 ft room with 8 ft walls, one door and one window.
How the calculator works
- Walls: 2 × (length + width) × wall height. Ceiling, if you include it: length × width.
- Openings: doors and windows × their width × height, subtracted from the wall area. For a room that isn't a rectangle, work out the floor area with the square footage calculator and measure the wall lengths directly.
- Sheets: board area plus the overage, ÷ the area of one sheet (32 ft² for 4 × 8, 40 for 4 × 10, 48 for 4 × 12), rounded up.
- Joint compound: about 10 gallons per 1,000 ft² of board. That's USG's published coverage for its ready-mixed all-purpose compounds, which come in 3.5 gal cartons.
- Paper tape: about 370 ft per 1,000 ft² of board, USG's figure for its paper joint tape. Rolls come in 75, 250 and 500 ft.
Worked example
A 12 × 12 ft bedroom with 8 ft walls, the ceiling included, one 36 × 80 in door and one 36 × 48 in window:
- Walls: 2 × (12 + 12) × 8 = 384 ft². Ceiling: 12 × 12 = 144 ft².
- Openings: 20 ft² (door) + 12 ft² (window) = 32 ft². Board area: 384 + 144 − 32 = 496 ft².
- Overage: under 1,000 ft², so 20%. 496 × 1.2 = 595.2 ft² ÷ 32 = 18.6, so 19 sheets of 4 × 8
- Compound: 496 × 10 ÷ 1,000 = 4.96 gal, so 2 cartons of 3.5 gal
- Tape: 496 × 370 ÷ 1,000 ≈ 184 ft, so one 250 ft roll
Assumptions and limits
- Overage: the default tiers come from USG's online estimator. That tool is for one of USG's ceiling systems, but the reasoning applies to any job: small jobs waste a bigger share to cut-offs and damaged sheets. Enter your own percentage if you've planned the sheet layout.
- Openings: many installers hang full sheets across doors and windows and cut the openings out afterward, and offcuts are rarely big enough to reuse. If you work that way, set doors and windows to 0.
- Layout isn't optimized. The calculator works by area. Longer sheets mean fewer joints to tape, but they're heavier and harder to get into a room.
- Screws aren't counted. USG specifies spacing, not a count: screws no more than 12 in apart on ceilings and 16 in apart on walls, and at least ⅜ in from panel edges, with heads set just below the surface without tearing the paper.
- Compound and tape are approximate. USG's figures assume normal three-coat finishing. Lightweight compounds, mesh tape, or a skim coat over the whole surface change the amounts. Also, USG's metric equivalent (37.8 L per 100 m²) is a loose rounding; the exact conversion of 10 gal per 1,000 ft², about 40.7 L per 100 m², is what the calculator shows in metric.
- Sheet sizes are US sizes. Metric-market boards are often 1200 × 2400 mm (about 31 ft²), so check what your store sells.
Related: once the walls are finished, the paint calculator works out primer and paint for the same room.
Turn off the power before cutting near outlets or switches, and check for wires and pipes before cutting into a wall. Ceiling sheets are heavy: use a helper or a rented drywall lift. USG's safety data warns that sanding dust can irritate the eyes, nose, throat and lungs, so work with ventilation, wear eye protection and a NIOSH-approved respirator, or wet-sand to cut dust. In homes built before 1978, painted surfaces may contain lead; see the EPA's guidance before you sand or demolish.
Sources
- USG, Sheetrock Brand Total joint compound submittal sheet (J1508) (PDF): coverage of about 10 gal per 1,000 ft², 3.5 gal carton, and the dust warning.
- USG, Sheetrock Brand paper joint tape submittal sheet (J1736) (PDF): about 370 ft per 1,000 ft², with 75, 250 and 500 ft rolls.
- USG, Sheetrock Brand installation and finishing guide (J371) (PDF): screw spacing.
- USG, Ensemble Estimator: suggested overage of 20%, 15% or 10% by project size.
- US EPA, Protect your family from sources of lead.