How Much Drywall for 400 Square Feet?
Drywall sheets
14 sheets
400 square feet of board, 4 by 8 sheets, ten percent waste.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Total area to cover400 sq ft
- Sheet size4 x 8 ft, 32 sq ft
- Waste allowance10 %
Drywall sheets14 sheets
| Area with 10% waste | 440 sq ft |
|---|---|
| Sheets at 32 sq ft | 14 |
| Joint compound, 4.5 gal buckets | 1 |
| Joint tape | 168 lf |
| Screws | 448 (about 2 lb) |
| Corner bead, rough guess | 27 lf |
The material list this produces
| Drywall sheets | 14 |
|---|---|
| Joint compound, 4.5 gal buckets | 1 |
| Joint tape, linear ft | 168 |
| Drywall screws, lb | 2 |
Sheet size compared
Longer sheets mean fewer butt joints and less taping. Same area, three sheet sizes.
| Sheet size | Drywall sheets |
|---|---|
| 4 x 8 ft | 14 sheets |
| 4 x 10 ft | 11 sheets |
| 4 x 12 ft | 10 sheets |
What else matters here
Four hundred square feet divided by 32 is 12.5 sheets. The answer on this page is 14, and the gap is the ten percent waste allowance, which is the number worth understanding rather than accepting.
Drywall waste is not spillage. It is the piece cut off the end of a wall that is four inches too narrow to use anywhere else, the sheet cut around a window that leaves two useless L shaped offcuts, and the sheet that gets a corner broken carrying it up a stairwell. Ten percent is the normal allowance for a plain rectangular room.
Push it to fifteen percent if the space has a lot of openings, angles or short walls, because every one of those is a cut with an offcut. A big open ceiling with no penetrations can run under five percent, which is why the allowance should follow the shape rather than the square footage.
What this calculator assumes
- Joint compound is figured at one 4.5 gallon bucket per 475 sq ft of board for a full three coat finish. A level 5 finish uses more.
- Tape is figured at 380 linear feet per 1000 sq ft of board, screws at 32 per sheet for 16 inch on center framing.
- Longer sheets mean fewer butt joints, which is less taping and a flatter wall. Use 12 footers where they will fit through the door.
Questions people ask
How many sheets of drywall for 400 square feet?
Fourteen sheets of 4 by 8, which is 12.5 sheets of bare coverage plus a ten percent waste allowance.
How much waste should I allow for drywall?
Ten percent for a plain rectangular room, fifteen for a space with lots of openings, angles or short walls, and less than five for a large open ceiling.
Why is drywall waste so high?
Because the offcuts are the wrong shape. A four inch strip off the end of a wall or an L shaped piece from around a window is rarely usable anywhere else.
The drywall calculator takes any dimensions you like and hands back the same list.