How to use the stud calculator
- Enter the wall length in feet.
- Choose the stud spacing: 16 in on centre is the most common for house walls; 24 in is used in some designs.
- Enter the corners or wall intersections and the door and window openings in this wall.
- Keep about 10% extra for warped or split studs and for blocking.
The result also gives the plate material: one bottom plate and a double top plate, so three times the wall length. Count door and window openings on your wall plan first: Decoratoradvice adds two studs for each opening you enter.
Stud formulas
Layout studs = (wall length ÷ spacing, rounded up) + 1
Studs to buy = (layout + 2 per corner + 2 per opening) × (1 + extra)
Plate length = 3 × wall length
The allowance of 2 per corner and 2 per opening is a planning figure. Corner and opening details vary with the framing method, so adjust it to your plans.
Worked examples
A 12 ft wall at 16 in on centre with no corners or openings:
144 in ÷ 16 in = 9 spaces
9 + 1 = 10 layout studs
With 10% extra: 11 studs
Plates: 3 × 12 = 36 ft
A 10 ft wall at 16 in with two corners and one window, no extra:
120 ÷ 16 = 7.5, rounded up to 8, + 1 = 9 layout studs
9 + (2 × 2) + (1 × 2) = 15 studs
Spacing options
| Spacing | Studs per 8 ft of wall (layout only) |
|---|---|
| 12 in | 9 |
| 16 in | 7 |
| 24 in | 5 |
Spacing for load-bearing walls depends on stud size, wall height and load, so follow your plans or local code.
Tips
- Mark the layout on both plates together so the studs line up top and bottom.
- Start the layout from the same end as the sheathing or drywall, so sheet edges land on studs. The drywall calculator and plywood calculator assume 4 ft sheets, which break on 16 in and 24 in layouts.
- Count studs for each wall separately, then add them, rather than using the total length of all walls.
Common mistakes
- Forgetting the final stud. Ten spaces need eleven studs.
- Ignoring corners and openings. Each adds framing beyond the regular layout.
- No allowance for bad studs. Some boards are too twisted to use.
Frequently asked questions
How many studs do I need for a 10 ft wall?
At 16 in on centre, 9 on the regular layout. Add extras for corners and openings, and about 10% for culls.
Should studs be 16 or 24 inches apart?
Sixteen inches is the usual spacing for house walls. Twenty-four inches uses less lumber but needs the right stud size and sheathing; follow your plans and local code.
How many studs per foot of wall?
At 16 in spacing, about 0.75 studs per foot plus one for the end. At 24 in, about 0.5 per foot plus one.
How many plates does a wall need?
Usually one bottom plate and two top plates, so plate material is three times the wall length.
Should I insulate the wall before drywall?
Yes, between the studs. The insulation calculator works out the thickness needed for a target R-value.
How do I price the lumber?
Studs are usually priced per piece. For hardwood or specialty stock priced by volume, use the board foot calculator.
Key takeaways
- Layout studs = wall length ÷ spacing, rounded up, plus one.
- Add studs for corners, openings and culls.
- Plate material is three times the wall length for a double top plate.
- Lay out from the same end as the sheet goods so edges fall on studs.