Sheets and finishing
Drywall calculator
Enter the walls and ceilings you are boarding. This gives sheets at your board size, then the screws, tape and compound needed to finish them.
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Longer board means fewer joints, and joints are the work
Hanging a 12 foot sheet instead of an 8 foot one on a long wall removes a butt joint completely. That matters more than the sheet count: a butt joint has no tapered edge, so it has to be floated out wide to disappear, and it is the joint every drywaller would rather not have.
The same 800 square feet takes 28 sheets of 4×8 or 19 sheets of 4×12. Fewer, larger sheets are harder to carry and easier to finish.
Sheets by board size
| Sheet | Area | For 800 sq ft plus 10% | Butt joints on a 12 ft wall |
|---|---|---|---|
| 4 × 8 ft | 32 sq ft | 28 sheets | One per row |
| 4 × 10 ft | 40 sq ft | 22 sheets | One per row |
| 4 × 12 ft | 48 sq ft | 19 sheets | None |
Screws are geometry once you know two spacings
A sheet hung across the framing crosses one member every spacing, and takes a screw every screw-spacing down each of them. A 4×8 sheet on 16 inch framing crosses 7 members, and at 12 inch screw spacing that is 5 rows: 35 screws a sheet.
Ceilings are fastened more tightly than walls because gravity is working against you, and the required spacing is set by code and by whether you are screwing to wood or steel. Set the spacing above to what applies to your job.
Hang ceilings first
Board the ceiling before the walls, so the top sheet on each wall pushes up and supports the ceiling edge. It is the difference between a tight corner and one you fill with compound.
Ignore small openings when you measure. A single door or window lands well inside the waste allowance, and the offcut around an opening is rarely big enough to use elsewhere. Deduct only for something genuinely large, like a garage door or a wall of glazing.
Common questions
How many sheets of drywall do I need?
Divide the total wall and ceiling area by the sheet area — 32 square feet for a 4×8, 48 for a 4×12 — then add waste. Eight hundred square feet plus ten percent is 28 sheets of 4×8.
How many screws per sheet of drywall?
About 35 for a 4×8 sheet on framing at 16 inches with screws every 12 inches. It is just the framing members the sheet crosses multiplied by the rows of screws down each one, which this calculator works out from your two spacings.
Should I use 8 ft or 12 ft drywall?
Twelve foot board where the wall is long enough, because it removes butt joints. Butt joints have no tapered edge and take the most finishing work of anything on the job. The trade-off is weight and manoeuvrability.
Do I subtract windows and doors from drywall?
Not for normal-sized ones — they fall inside the waste allowance and the offcuts are rarely reusable. Deduct only for very large openings.
How much joint compound do I need?
It depends on the product and the level of finish, so read the coverage on the bucket and enter it above. There is no useful universal figure, which is why this calculator asks rather than guesses.
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