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Studs needed
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including waste
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linear ft total
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Framing reference

Stud spacing guide

16" O.C. — most common residential, suits standard 4×8 sheet goods · 24" O.C. — economy framing, structural panels required · 12" O.C. — heavy loads, tall walls, or high wind/seismic zones · 400mm / 600mm — metric equivalent of 16"/24".

Lumber sizes (actual vs nominal)

2×4 nominal = 1.5"×3.5" actual · 2×6 nominal = 1.5"×5.5" actual · 2×3 nominal = 1.5"×2.5" actual. Stud length for 8ft ceiling: 92⅝" (pre-cut studs) or cut from 8ft lengths allowing for plates.

Plate configuration

Standard: 1 bottom plate + 2 top plates = 3 plates total · Load bearing walls always use double top plate · Partition walls may use single top plate · Bottom plate: pressure treated if touching concrete.

Noggins / blocking

Noggins (UK) = blocking (US). Typically 1 row at mid-height for walls under 3m (10ft). Required for: fire blocking, drywall backing at joints, lateral bracing. Stagger for easier nailing.

The O.C. rule

"On centre" (O.C.) means the distance from the centre of one stud to the centre of the next. A 16" O.C. wall has studs every 16 inches measured centre-to-centre, not edge-to-edge.

Stud Spacing Calculator — Wall Framing & Materials List

Free tool · Works offline · 16" & 24" O.C. · Metric & imperial

How many studs do I need?

The formula is: (Wall length ÷ Stud spacing) + 1, rounded up, plus 10% for waste and extras. For a 16 ft wall at 16" O.C.: (16 × 12) ÷ 16 + 1 = 13 studs. Add 10% = 15 studs. Always add extra studs for corners (3-stud corner assemblies), door and window rough openings (king studs, jack studs, cripples), and partition wall intersections. The multi-wall tab in this calculator builds a full materials list automatically.

16 inch vs 24 inch stud spacing — which is right?

16" O.C. (400mm) is the standard for most residential construction. It suits standard 4×8 sheet goods (plywood, OSB, drywall) and provides a solid nailing surface every 400mm. Required for load-bearing walls, walls over 3m tall and high wind/seismic zones. 24" O.C. (600mm) uses about 30% less lumber, reducing cost and thermal bridging. It requires thicker sheathing (½" minimum OSB) and may not be permitted for load-bearing applications in your area. Always check your local building code.

What lumber size should I use for wall framing?

2×4 (38×89mm actual) is the standard for most interior partitions and exterior walls in mild climates. 2×6 (38×140mm) is used for exterior walls in cold climates — the extra depth allows for more insulation (R-21 vs R-15). 2×3 (38×63mm) is used for non-structural partitions where space is tight. Stud length depends on ceiling height — for 8ft (2.44m) ceilings, pre-cut studs are 92⅝" (2,355mm), accounting for a double top plate and single bottom plate.

How to calculate plates and noggins

Plates: Each wall needs a bottom plate and typically two top plates (double top plate for load-bearing walls). Total plate length = wall length × 3. For a 16ft wall: 48 linear ft of plate. Noggins (blocking): Horizontal members between studs at mid-height. Required for fire blocking, drywall backing at horizontal joints, and lateral bracing. For a standard 8ft wall: one row of noggins at 4ft. Total noggin length = (number of spaces between studs) × stud spacing.

Frequently asked questions

How many studs for a 12 foot wall?

At 16" O.C.: (12 × 12) ÷ 16 + 1 = 10 studs. Add corner/opening allowance and 10% waste = 12–13 studs typically. At 24" O.C.: 7 studs + allowances = 9–10 studs.

Do I need blocking between studs?

Fire blocking is required by code in walls over 8ft (2.44m) tall. Horizontal blocking at drywall joints prevents waviness. Always add blocking where fixtures will be mounted — TV brackets, grab bars, heavy shelving.

What is the rough opening size for a door?

Add 2" (50mm) to the door width and 2.5" (63mm) to the door height for the rough opening. A 32" door needs a 34" rough opening. The calculator's opening tab handles this automatically.

Can I use engineered lumber for wall framing?

Yes — LVL (laminated veneer lumber) and LSL (laminated strand lumber) are stronger and straighter than dimensional lumber, making them ideal for long spans and header beams. For standard studs, dimensional lumber is still the norm.