Drywall partition· 5 min read
How to Calculate a Drywall Partition: How Many Studs, Boards and Screws
A 4 × 2.75 m metal stud wall boarded on both sides: how many CW studs and UW tracks, boards, screws, filler, tape and insulation to buy and what a door changes.
A drywall (plasterboard) partition is a metal frame of studs and tracks, boarded on both sides with mineral wool inside. The materials can be counted exactly — studs and boards by the piece, screws and filler by the area. We'll use the wall for which Knauf publishes its average material consumption, so you can compare the result with the manufacturer.
Example: a wall 4 × 2.75 m
- Size: 4.00 m long, 2.75 m high — 11 m² per side.
- Frame: CW 50 studs at 625 mm centres in UW 50 floor and ceiling tracks. Studs are 15 mm shorter than the room height: 2,735 mm.
- Boards: one layer of 1250 × 2750 mm boards on each side. The boards are room-high, so there are no horizontal joints.
- Insulation: mineral wool over the whole wall.
Why 625 mm: every vertical board edge must land on a stud. A 1,250 mm board then sits on three studs — one at each edge and one in the middle.
Studs and tracks
CW studs stand at 0, 625, 1,250 … 3,750 mm plus one against the far wall: 8 studs of 2,735 mm, cut from 8 lengths of 2.75 m. The UW track runs the full length on the floor and on the ceiling: 8 m, two 4 m lengths.
Boards, screws, filler and tape
- Boards: 4 per side, 8 in total, 22 m². Side A starts with a full board at the wall; side B is shifted by one stud spacing (625 mm) so the vertical joints of the two sides are not on the same stud.
- Screws: with one layer the screws are at most 250 mm apart, which Knauf averages at 15 screws per m² of board. 22 m² × 15 = 330 screws.
- Filler: 0.25 kg per m² of board, 5.5 kg in total.
- Joints: three vertical joints per side, 16.5 m. With a filler like Knauf Uniflott, tapered long edges are filled without tape and tape goes on cut ends; other systems tape every joint — so the calculator gives the full joint length.
- Insulation: 11 m², thickness to suit the stud size and the sound insulation you need.
- Sealing tape under the tracks and edge studs: the wall perimeter 2 × 4 + 2 × 2.75 = 13.5 m.
- Fixings: tracks and edge studs fixed at most 1 m apart, at least 3 per edge stud — 18 fixings.
| Item | Knauf per m² of wall × 11 m² | Calculator |
|---|---|---|
| CW studs | 2.0 m → 22 m | 8 × 2,735 mm = 21.88 m |
| UW track | 0.7 m → 7.7 m | 8 m |
| Screws | 30 → 330 | 330 |
| Filler (Uniflott) | 0.5 kg → 5.5 kg | 5.5 kg |
| Sealing tape | 1.2 m → 13.2 m | 13.5 m |
| Fixings | 1.6 → 17.6 | 18 |
Knauf's figures are averages from the material table in its technical document W11.ch (03/2026), drawn up for exactly this 4.00 × 2.75 m wall. The calculator counts real pieces, so it differs only by rounding. Neither includes waste — add a reserve.
The English calculator works per square foot, so the link opens it with Knauf's rates converted: 1.3935 screws per sq ft is 15 per m², 5.12 lb filler per 100 sq ft is 0.25 kg per m².
Drywall partitionOpen the 4 × 2.75 m wall in the calculatorAdding a 900 × 2,050 mm door
Now put a 900 × 2,050 mm rough opening into the same wall, 1,450 mm from the start (take the exact opening size from the door frame you buy). The frame changes like this:
- Door studs: a full-height stud on each side of the opening. The stud at 1,875 mm falls into the opening, so only a 685 mm piece above the lintel is left of it. Full-height studs: 7 regular + 2 door studs.
- Lintel: a piece of UW track across the top, 150 mm past each side: 1,200 mm.
- Floor track is cut out across the opening, leaving 1,450 and 1,650 mm. Track in total: ceiling 4 m, floor 3.1 m, lintel 1.2 m — three 4 m lengths.
- Stud lengths: 8 × 2.75 m and 1 × 4 m, which gives a door stud and the 685 mm piece.
| Item | No door | With door |
|---|---|---|
| Wall area (one side) | 11 m² | 9.155 m² |
| CW lengths | 8 × 2.75 m | 8 × 2.75 m + 1 × 4 m |
| UW lengths 4 m | 2 | 3 |
| Boards 1250 × 2750 mm | 8 | 8 |
| Screws | 330 | 275 |
| Filler | 5.5 kg | 4.6 kg |
| Joints | 16.5 m | 14.45 m |
| Insulation | 11 m² | 9.15 m² |
| Sealing tape | 13.5 m | 12.6 m |
| Fixings | 18 | 19 |
Still 8 boards — the opening is cut out of them and the piece above the door is too small to save a whole board. Screws, filler and insulation go down with the area; fixings go up because the floor track is now two pieces.
Watch out: at 2.75 m, CW door studs are not enough
Knauf (citing the German standard DIN 18340) allows ordinary CW studs beside a door only for walls up to 2.60 m, doors up to 0.90 m wide and door leaves up to 25 kg. Our wall is 2.75 m, so the door needs reinforced UA profiles of 2 mm steel, fixed with brackets at top and bottom. Of the 9 full-height studs in the table, 2 are door studs — buy those as UA. More in the article on double layers and doors.
Drywall partitionOpen the wall with the doorThe calculator works out quantities and layout, not structural design. Maximum wall height, stud size and spacing, door framing, fire and sound ratings must follow your board maker's system and local regulations.