Worked example: drywall for a 12 × 14 ft room
Hypothetical educational example. Sheets use a 10% site allowance. The compound line on the calculator is a rule of thumb in pounds. USG’s current all-purpose submittal states gallons. This page shows both and does not add them.
Inputs
| Room | 12 × 14 ft |
|---|---|
| Wall height | 8 ft |
| Ceiling | included |
| Openings | 1 door at the calculator’s 20 sq ft, 2 windows at 15 sq ft each |
| Sheet | 4 × 8 ft (32 sq ft) |
| Waste | 10% |
Arithmetic
- Walls = 2 × (12 + 14) × 8 − 50 = 366 sq ft. Ceiling = 168 sq ft. Total = 534 sq ft.
- 534 × 1.10 ÷ 32 = 18.36, which rounds up to 19 sheets.
- USG’s about 10 gal per 1,000 sq ft gives 5.34 gal on 534 sq ft. Two 4.5 gal containers cover that if that is the pail you buy.
- The calculator instead prints about 73 lb and 2 × 62 lb pails, and about 611 screws on the purchased sheet area. Those are site rules, not the USG gallon rate or the USG spacing schedule.
Required, waste and purchase
- Required
- 18.36 sheets before rounding, or 5.34 gal of all-purpose compound at the USG rate, before container rounding.
- Purchased
- 19 sheets. Two containers if you follow either the 4.5 gal illustration or the calculator’s 62 lb pail label. Do not buy both the gallon estimate and the pound estimate for the same coats. Screw purchase is not a box count, because no screws-per-box figure is cited.
- Units
- US feet and 4 × 8 ft sheets. Gallons are US gallons.
Assumptions
- Door and window areas are the calculator constants, not a tape measurement of a real opening.
- 10% waste is not from USG’s estimator, which says its estimate excludes waste.
What this example does not decide
- Not a fire-rated or acoustic assembly. Those specify their own fastener spacing.
- Insulation in the wall cavity is a separate calculator and is not included in the 19 sheets.
Where to go next
- Drywall calculator — Run these inputs
- Drywall topic — Sheets versus gallon coverage
- Sheet sizes guide — US, UK and Australian boards
- Paint calculator — Coats after the board is finished
- Insulation calculator — A separate cavity order
Questions
Should I add the 73 lb figure to the 5.34 gallons?
No. They are two descriptions of finishing compound. The pounds come from this site’s 0.67 kg per square metre rule. The gallons come from USG’s all-purpose submittal. Pick the product you are buying.
Are 611 screws a USG requirement?
No. The calculator multiplies about 10.8 screws per square metre by the area of the 19 sheets you buy. USG states maximum screw spacing, 12 inches on ceilings and 16 inches on walls, and does not state that 611 count.
Sources
- USG Sheetrock all purpose joint compound submittal J1969 — accessed 2026-11-09: “Coverage: Approximately 10 gal./1,000 sq. ft. (37.8 L/100 sq. m) of gypsum panels.”
- USG – Sheetrock wallboard estimator — accessed 2026-11-09: “This estimate doesn't include an allowance for waste.”