Understanding your result
The headline gives the two figures that decide the trip to the lumber yard, studs and sheets, and the line under it restates the wall. The tiles give the plates, the screws, the compound and, if you ticked it, the insulation.
The table is the full list in the order you will use it: studs and their length, plates, headers, then the face area after the door openings, the sheets for one or both sides, screws, tape, compound for the finish level you chose, and insulation. Each line uses the same rules as the dedicated calculator for that material: the wall stud calculator for the framing, the single wall calculator for the board layout, the joint compound coverage for the finish.
The door openings come out of the board area at the height of the rough opening, and the header length is the rough opening plus 3 in. If you only know the door size, the rough opening calculator gives the opening. The trim and flooring on both sides of the new wall are another trade; Floorings Calculator, our sister site at flooringscalculator.com, counts the baseboard.
How we calculate this
The stud count, the screw pattern and the compound coverage are the site’s shared tables: field studs at the spacing with kings, jacks and cripples at each door; 28 screws per 4 × 8 sheet on 16 in studs; 9.4 gallons of compound per 1,000 sq ft at Level 4, pro-rated for the other levels on the coverage table. Insulation coverage is Rockwool’s published pack coverage for 3 in Safe’n’Sound mineral wool sized for 2 × 4 walls; other products list their own coverage on the bag.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Wall type | Non-load-bearing partition | Scope of the site; bearing walls need span tables |
| Studs | 16 in on centre, 92-5/8 in precuts for 8 ft | IRC Table R602.3(5); standard precuts |
| Door rough opening | 34 in × 82-1/2 in | A 32 in pre-hung door |
| Screws | GA-216 wall spacing | Gypsum Association GA-216 |
| Compound | 9.4 gal per 1,000 sq ft at Level 4 | USG product data |
| Insulation coverage | 59.7 sq ft (15-1/4 in) or 60.1 sq ft (23 in) per pack | Rockwool Safe’n’Sound 3 in mineral wool product data |
| STC with insulation | About 36–39 for a single wood-stud wall | GA-600 published assemblies; see the assemblies page |
| Waste | 10% | Studs and board |
Assumptions last reviewed October 8, 2026.
The calculator does not count electrical boxes and wire, the door itself, casing, baseboard or paint, and it does not plan blocking for cabinets, which the plates and blocking calculator adds. The full sequence, from snapping the line to taping the last corner, is in the guide to framing a partition wall; the board count method is in the guide to counting sheets.
Two worked examples
A 10 × 8 ft wall with a 36 in door, both sides, insulated
Rough opening 38 in, 16 in studs, 4 × 8 sheets, Level 4.
- Studs: 14 → 16 with waste, 92-5/8 in; plates 30 ft; one header 41 in long
- Face area: 80 − 22 = 58 sq ft per side; board 116 sq ft → 5 sheets of 4 × 8
- 140 screws, 96 ft of tape (1 roll), 1.1 gallons of compound (1 pail), 1 pack of insulation
Most of the cost of a short wall is the door and its trim, not the wall; the board and compound for both sides fit in the back of a car.
A 16 × 9 ft wall with no door, 4 × 12 sheets, Level 5, insulated
- Studs: 15 → 17 with waste, 104-5/8 in; plates 48 ft
- Board: 144 sq ft per side, 288 sq ft → 7 sheets of 4 × 12
- 280 screws, 164 ft of tape, 4 gallons of compound for Level 5 (1 pail), 3 packs of insulation
Twelve-foot sheets on a 16 ft wall leave a 4 ft piece per row, which is why the waste is a sheet; on a 12 ft wall the same sheets would fit exactly.
Where to find your inputs
Length and height. The wall line on the floor and the height from floor to ceiling.
Doors. How many, and the rough opening width; a 36 in door has a 38 in opening.
Sides. Both, unless one side faces an unfinished space.
Finish level and insulation. Level 4 for painted walls; insulation if you want privacy between the rooms.
Common mistakes
- Building on top of the finished floor without thinking about it. Decide whether the wall sits on the subfloor or the finished floor before you cut studs; it changes the stud length.
- No fixing at the ceiling. A wall parallel to the joists needs blocking between them to fasten the top plate to.
- Forgetting the outlets. A new wall often needs outlets by code; plan the wiring before the board.
- Insulation after one side is boarded. Fit the batts from the open side before the second side goes on.
- Board touching the floor. Leave 1/2 in at the bottom; the baseboard covers it.
- Creating a bedroom without egress. A new bedroom needs an egress window and smoke alarms. Check the code.
Questions people ask
- What materials do I need to build an interior wall?
- For a 12 × 8 ft wall with one door, both sides boarded, about 18 studs of 92-5/8 in, 36 ft of plate, a short 2 × 4 header, 6 sheets of 4 × 8 drywall, about 170 screws, a roll of tape, a pail of compound and two packs of mineral wool if you want it quieter. The calculator lists all of it for your size.
- How much does it cost to build a partition wall?
- Materials for a 12 ft wall boarded on both sides typically run a few hundred dollars: lumber, about six sheets of drywall, fasteners, compound and insulation. Labour depends on the region and the finish level; the drywall cost estimator prices the board and finishing.
- Do I need a permit to build an interior wall?
- Often, yes. Many jurisdictions require a permit for new walls, especially if they create a bedroom (which needs egress and smoke alarms) or move electrical outlets and switches. Check with your building department before you start.
- Should I insulate an interior wall?
- For sound, yes. Fibreglass or mineral wool batts in the cavity raise a single-stud wall from about STC 33 to 35 to about 36 to 39 in published GA-600 assemblies. For more privacy, a second layer of board or resilient channel on one side adds more.
- How do I attach a new wall to the ceiling?
- If the wall runs across the joists, nail or screw the top plate to each joist. If it runs parallel and between joists, fit blocks between the two nearest joists every 24 in and fix the plate to the blocks. Fix the bottom plate to the floor framing or, on concrete, with concrete screws through a pressure-treated plate.
- How long does it take to build a partition wall?
- Framing a 12 ft wall with a door is a day for one person; hanging the board both sides is half a day; taping and finishing to Level 4 is four or five days, mostly drying time. Call it a week from layout to paint for a careful DIYer.