How to calculate how many studs you need
- Measure the wall length in feet. For a whole house, add up all wall lengths.
- Choose the spacing — 16 in on center is standard; 24 in is common for some exterior walls and advanced framing.
- Divide and add one for the end stud of each wall.
- Add extras for corners, intersections and openings, then 10% for warped or split studs.
Stud formula
Extra studs ≈ 2 per corner + 2 per intersection + 2 per opening
Worked example: a 40 ft wall
At 16 in on center, 40 × 12 ÷ 16 = 30 spaces, so 31 studs on layout. Two corners and two openings add 8 studs, for 39. With 10% for culls, buy 43 studs. A double top plate and single bottom plate need 120 linear ft of plate stock — nine 16 ft boards with 10% waste.
Corners, tees and openings
- Corners: a corner needs extra studs so there is backing for drywall on both walls. Two extras per corner is a common allowance (three-stud corner); advanced framing can use fewer with drywall clips.
- Intersections (tees): where an interior wall meets another wall, add backing — about two studs, or a ladder block.
- Openings: each door or window gets a king stud on each side. Jack (trimmer) studs, the header and short cripple studs above and below the opening are extra, and depend on the opening's size.
Stud count chart
Studs on layout for a single straight wall (before extras and waste):
| Wall length | 16 in on center | 24 in on center |
|---|---|---|
| 8 ft | 7 | 5 |
| 10 ft | 9 | 6 |
| 12 ft | 10 | 7 |
| 16 ft | 13 | 9 |
| 20 ft | 16 | 11 |
| 24 ft | 19 | 13 |
| 40 ft | 31 | 21 |
A quick rule of thumb: about one stud per linear foot of wall at 16 in on center once corners and openings are included.
Plates and stud lengths
Most load-bearing walls have a single bottom plate and a double top plate, so plate lumber is about three times the wall length. Precut studs save cutting: in the US, 92⅝ in studs with a bottom plate and double top plate (each 1½ in thick) give a wall 97⅛ in tall — enough for 8 ft drywall on the wall and a ½ in ceiling. 104⅝ in studs suit 9 ft walls.
Code basics
Building codes limit stud size, spacing and height for load-bearing walls — for example, 2×4 studs in bearing walls are commonly limited to 16 in on center when they support a roof plus a floor, and to 24 in when they support only a roof and ceiling. Exterior walls also need structural sheathing or bracing. Check the stud spacing tables in the International Residential Code (Section R602) or your local code. Estimate wall sheathing and drywall with the drywall calculator, and lumber volume with the board foot calculator.
Frequently asked questions
How many studs do I need for a 10 ft wall?
At 16 in on center, 9 studs on layout. Add extras for any corners or openings and about 10% for waste.
How do you calculate studs at 16 inches on center?
Multiply the wall length in feet by 12, divide by 16, round up and add 1. Then add extras for corners, intersections and openings.
How many studs per linear foot of wall?
About 0.75 at 16 in on center on layout, or roughly one per foot once corners, openings and waste are included.
Are 24 inch stud spacings allowed?
Often yes for non-bearing walls and for bearing walls that carry only a roof and ceiling, depending on stud size and height. Check your local code tables.
How much plate lumber do I need?
About three times the wall length for a double top plate and single bottom plate, plus waste.
Sources & standards
This calculator's formulas and default values are based on the following codes, standards and published data. Codes are adopted and amended locally, so check with your building department for permitted work. See how we build and check our calculators.
- International Residential Code (IRC) R602.3: wood wall framing, stud size, height and spacing (Table R602.3(5)) and double top plates (R602.3.2).
- American Wood Council, Wood Frame Construction Manual and advanced framing guidance.
- US Department of Energy, advanced framing (optimum value engineering) technical fact sheets.