Formula
Net area is length × height minus openings. Sheets are that area times one plus waste, divided by 32 or 48, rounded up. A 12 × 8 wall is 96 ft². At 10% waste a 4 × 8 sheet needs four sheets. With no waste it would be three.
across = ceil(length / 4)
courses = ceil(height / sheet height)
tape = (across − 1) × height + (courses − 1) × length
That tape length assumes the sheets hang in a grid, full sheets, not staggered. A 12 × 8 wall with 4 × 8 sheets is three across and one course: 16 ft of vertical seam and no horizontal seam. Mud defaults to 1 gallon of ready-mix per 100 ft² of net area. Screws default to 32 per sheet. Neither is a USG number. The tile calculator is the finish on the other side of the room.
Worked examples
12 × 8 ft, no openings, 10% waste, 4 × 8 sheets. Four sheets. Tape 16 ft. Mud 0.96 gal. Screws 128.
The same wall with no waste. Three sheets. The seam count does not change, because it follows the wall, not the waste.
A 20 ft² door subtracted. Net area 76 ft². Sheets use 76 × 1.10 / 32. Tape stays 16 ft.
Reference
Planning rates. Replace them with the bucket and the screw schedule you are actually using.
| Item | Default |
|---|---|
| Sheet | 4 × 8, 32 ft², or 4 × 12, 48 ft² |
| Waste | 10% |
| Mud | 1 gal per 100 ft² |
| Screws | 32 per 4 × 8 |
Questions
Does one gallon per 100 square feet come from USG?
No. It is a planning rate for ready-mix on this page. The bucket you buy prints a coverage. Use that.
Why 32 screws?
A planning count, about a foot apart in the field of a 4 × 8 sheet. It is not a USG fastening schedule. Type the count your assembly calls for.
How is the tape measured?
Sheets are assumed to hang in a grid. Vertical seams are one less than the number of sheets across, times the wall height. Horizontal seams are one less than the number of courses, times the length. Openings are removed from the area, not from the seams.
Sources
- Sheet count is net area × (1 + waste) / sheet area, rounded up. Tape assumes a grid of sheets.
- One gallon per 100 ft² and 32 screws per sheet are planning defaults for this page, not a USG coverage or fastening table.