What this calculator does
Stud wall spacing is the on-centre distance between the vertical framing members that make up a timber or metal-stud wall. This calculator turns a wall length and a chosen spacing into the number of studs the run actually needs, plus two extra studs for every door or window opening to carry the trimmers either side.
Standard wall framing stud spacing varies by region and by what the wall carries. US residential framing commonly uses 16 or 24 inches on-centre; Australian and other metric-standard framing commonly uses 450 or 600 mm on-centre, and load-bearing walls, tall walls or heavier cladding can call for tighter spacing again. Because the correct figure depends on the local building code, the wall height, and what loads it carries, the spacing here is always something you enter yourself rather than a fixed default.
The formula
Divide the wall length by the on-centre spacing, round up, and add one stud to close out the run. Each door or window opening then needs an extra stud on each side to support the header and sill, so two are added per opening.
| Term | Meaning |
|---|---|
| On-centre spacing | The distance measured from the centre of one stud to the centre of the next, not the clear gap between them. |
| Trimmer stud | An extra stud placed alongside an opening to help carry the header above a door or window. |
| Wall length | The total horizontal run of the wall being framed, before any openings are subtracted. |
The inputs explained
| Field | What to enter |
|---|---|
| Wall length (m) | The total length of the wall run being framed. |
| Stud spacing (on-centre) (mm) | The on-centre stud spacing your framing plan or local code calls for, such as 450 mm, 600 mm, 16 inches or 24 inches converted to millimetres. |
| Number of door/window openings | How many door or window openings interrupt this wall run. |
When to use it
Ordering timber for a new wall
Knowing the exact stud count before a delivery is booked avoids both a wasted second trip for a handful of extra studs and paying for timber that never gets used.
Checking a supplied framing plan
Recomputing stud count from the stated wall length and spacing is a quick way to sanity-check a quote or a plan set before work starts.
Comparing spacing options
Tightening the spacing from 600 mm to 450 mm, or from 24 inches to 16 inches, raises the stud count on the same wall; running both figures side by side shows the actual cost of moving to a stiffer wall.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many studs does a wall need at different spacings?
A fixed 6 m wall with one door opening, framed at a range of common on-centre spacings.
How does wall length change the stud count at a fixed spacing?
A fixed 450 mm spacing with no openings, across a range of wall lengths.
Questions
What stud spacing should I use?
It depends on the local building code, whether the wall is load-bearing, its height, and the cladding or lining being fixed to it. Common defaults are 16 or 24 inches on-centre in US framing, and 450 or 600 mm on-centre in Australian and other metric framing, but always check the code or engineering documents that apply to the specific job rather than assuming a default.
Why add two studs per opening instead of one?
A door or window opening needs a trimmer stud on each side to help support the header that spans the opening, plus the jack framing below a sill if there is one. Two extra studs per opening is the standard allowance for that extra framing.
Does this account for corner studs or wall intersections?
No. This calculator counts field studs along a single straight run at the given spacing. Corners, T-intersections and blocking for fixtures are typically added separately according to the specific framing detail being used.
Is this the same maths as spacing roof trusses?
The underlying on-centre spacing calculation is similar to the roof truss count calculator, but studs and trusses are different building elements with different typical spacings, load paths and code requirements, so they are kept as separate calculators.
For the roof framing above this wall, see the roof truss count calculator. For working out how much timber the studs themselves will cost, a board-on-board fence calculator shows a similar length-and-spacing material takeoff for fencing.