How to use the stud calculator
- Enter the total wall length. For a room or shed, add every wall you are framing.
- Choose the spacing: 16 inches on center is standard for most house walls; 24 inches is common for some non-bearing and advanced-framing walls; 12 inches for heavy loads or tall walls.
- Count outside corners and wall intersections. Each adds about two studs for corner and nailing backing.
- Count doors and windows. Each opening adds roughly four studs: two king studs and two jack (trimmer) studs. Studs that fall inside the opening become cripples above and below, so they are not subtracted.
- Set plate rows: one bottom plate plus a double top plate is three rows.
The stud formula
Layout studs = round up (wall length (in) ÷ spacing) + 1
Studs = layout studs + 2 × corners + 2 × intersections + 4 × openings, + waste
Plate lumber = wall length × plate rows
The extra "+1" is the end stud: a 16 ft wall at 16 inches has 12 spaces but 13 studs. A quick rule many framers use is one stud per linear foot of wall at 16 inches on center, which roughly covers corners, openings and culls on an average wall.
Worked example
A 20 ft wall at 16 inches on center, two outside corners, one door and one window, three plate rows, 10% waste:
- Layout studs: 240 ÷ 16 = 15, + 1 = 16
- Extras: 2 × 2 (corners) + 4 × 2 (openings) = 12
- Total: 28; with 10% waste 31 studs
- Plates: 20 × 3 = 60 linear ft = 4 boards of 16 ft
16 vs. 24 inches on center
The International Residential Code (Table R602.3(5)) sets maximum stud spacing based on stud size, wall height and how many floors the wall supports. For example, 2×4 bearing walls are commonly framed at 16 inches, and 24 inch spacing is allowed in some cases such as walls supporting only a roof. Spacing also has to suit the sheathing and drywall, which are sized to land on 16 or 24 inch centers. Check your local code and plans for bearing walls.
Stud lengths
- 8 ft walls: precut studs are 92 5/8 in. With a bottom plate and double top plate (3 × 1.5 in), the framed wall is 97 1/8 in, leaving room for 8 ft drywall plus ceiling drywall.
- 9 ft walls: precut 104 5/8 in studs.
- 10 ft walls: precut 116 5/8 in studs.
A 2×4 stud actually measures 1.5 × 3.5 inches and a 2×6 1.5 × 5.5 inches under the American Softwood Lumber Standard (PS 20).
Other framing lumber to remember
- Headers over every door and window, sized for the span and load.
- Blocking for cabinets, grab bars, TVs and fire blocking where required.
- Sheathing: the plywood calculator converts wall length × height into sheets.
- Rafters for a shed or addition: see the rafter calculator.
Frequently asked questions
How many studs do I need for a 10 ft wall?
At 16 inches on center, a 10 ft (120 in) wall needs 120 ÷ 16 = 7.5, rounded up to 8, plus 1 = 9 studs, before adding any for corners or openings.
How many studs are in a 12 ft wall at 16 on center?
A 12 ft wall is 144 inches: 144 ÷ 16 = 9 spaces, so 10 studs on the layout, plus extras for corners, intersections and openings.
How do you calculate studs for a wall?
Divide the wall length in inches by the spacing, round up and add one. Then add about two studs per corner or intersection and four per door or window, plus 10% for waste.
Is one stud per foot a good estimate?
Yes, for 16 inch on-center framing, one stud per linear foot of wall is a common quick estimate that covers typical corners, openings and culls.
How long are studs for an 8 foot wall?
Precut studs for 8 ft walls are 92 5/8 inches. With one bottom plate and a double top plate, the wall frames out at 97 1/8 inches.