Stud Calculator — Wall Studs at 16″ or 24″ OC
Calculate how many studs you need for a wall, plus plates, drywall and insulation. Enter wall length and height, pick 16 in / 24 in (400/600 mm) on-centre spacing, add openings, and get a complete framing material list.
How many studs do I need for a wall?
Wall length ÷ spacing, rounded up, plus one to close the end, plus a doubled stud each side of every opening. A 3.6 m (12 ft) wall at 400 mm (16 in) centres is 9 studs plus the end one; a 6 m (20 ft) wall is 15 plus the end. Add the header and any cripples above a door on top of that.
Is 16 or 24 inch on centre right?
16 in (400 mm) is the default for load-bearing walls and anywhere the finish needs support — it also suits standard 48 in sheet widths. 24 in (600 mm) is common for non-bearing partitions and saves timber, but wants thicker board to stop it dishing between studs. Local codes and span tables decide it, not preference.
Wall diagram
Shopping list — 48×98 mm C24
Framework
Fasteners
Cladding
Insulation
Trims and surface
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How the stud count is calculated
- 1Studs: wall length ÷ on-centre spacing, rounded up, + 1 end stud
- 2Add doubled studs at each side of every door and window opening
- 3Plates: bottom plate + top plate = 2 × wall length (double top plate on load-bearing walls)
- 4Stud length = wall height − combined plate thickness
- 5Drywall and insulation follow from the wall area
- 6Add 10% waste — crooked studs get culled at the yard and on site
Worked example
Partition wall: 4.8 m (≈ 16 ft) long, 2.4 m high, studs at 400 mm (16 in) OC, one door opening.
13 studs (12 + end stud) + 2 doubled at the door = 15 studs, plus 9.6 m of plate material — 32 linear feet.
Frequently asked questions
How many studs do I need for a 12-foot wall?
At 16 in OC: 144 ÷ 16 = 9, +1 end stud = 10 studs — before adding doubles at openings and corners. At 24 in OC: 7 studs. A rough rule: one stud per foot of wall covers extras.
Should I frame at 16 or 24 inches on centre?
16 in (400 mm) is the default for load-bearing walls and anything carrying tile or heavy shelving. 24 in (600 mm) saves lumber on non-load-bearing partitions with standard 12.5 mm drywall.
What are king and jack studs?
At each side of an opening, a full-height king stud runs plate to plate, and a shorter jack (trimmer) stud under it carries the header. That's why the calculator adds two studs per side of a door or window.
How long is a wall stud?
Stud length = wall height minus the plates. US precut studs are 92 5/8 in — sized so that with three plates the wall comes out at standard 8 ft ceiling height. Metric framing typically cuts studs from 2.4 m or 3.0 m stock.
Do corners need extra studs?
Yes — a corner where two walls meet needs 2–3 studs arranged to give both walls a fixing edge for drywall. Add 2 extra studs per corner to the calculated count.