How many studs do I need?
Count one stud at every spacing mark plus one at the far end, then add for corners and openings: studs = (wall length ÷ stud spacing, rounded up) + 1, plus about 2 per corner and 2 per door or window, then a waste allowance. A 20 ft wall at 16 in on-center comes to 16 studs for the run; add one opening and a 10% waste allowance and you would buy about 20 studs.
Rather skip the arithmetic? Use the framing calculator → Enter the wall length, the stud spacing and how many corners and openings it has, and it returns the stud count and the plate lumber the moment you type.
1. The stud-count formula
Framing a wall is, at heart, a counting job, and the count follows one short rule. Studs sit at a fixed spacing along the wall — most often 16 inches (about 400 mm) or 24 inches (about 600 mm) on center — so the number of gaps between them, the bays, is the wall length divided by that spacing, rounded up. Because a stud sits at both ends of the wall and not just at the start of each bay, the number of studs for a plain run is the number of bays plus one. That single “plus one” is the step most rough estimates forget, and it is why a quick “one stud per foot” guess always comes out slightly short.
On top of the run you add a handful of studs where the framing does more than carry the wall above. Corners need extra studs so the drywall has something to fasten to on both walls, and every door or window opening needs jack studs to carry its header alongside the full-height king studs. A sensible planning allowance is about two extra studs per corner and two per opening; wide openings and built-up corners can need more. Finally, you add a waste allowance, because some pieces arrive bowed, split or crowned badly enough to cull. Put together, that is: studs = bays + 1 + corner extras + opening extras, all multiplied by one plus the waste fraction.
2. A worked example
Take a straight wall 20 feet long, framed at 16 inches on center, 8 feet tall, with one doorway and no extra corners. Twenty feet is 240 inches; divided by 16 that is exactly 15 bays, so the run needs 16 studs. The single opening adds roughly 2 jack studs, bringing the total to 18. Apply a 10% waste allowance — 18 × 1.10 is 19.8 — and round up, and you would buy 20 studs. The same wall framed at 24 inches on center is 10 bays, so 11 studs for the run, 13 with the opening, and about 15 after waste: fewer studs, but a less rigid wall with less nailing surface.
Don't forget the plates — the horizontal members the studs sit between. A typical wall has three rows: a single bottom plate and a double top plate. The plate lumber is simply the wall length times the number of rows, so our 20 ft wall needs about 60 feet of plate stock. Add the studs themselves (20 studs × 8 ft ≈ 160 lineal feet) and you have the full lumber take-off for the wall. The framing calculator reports all of this — studs, plate length and total stud lumber — as you change the inputs.
3. Studs per wall, at a glance
This chart shows the studs needed for a straight wall run — that is, bays plus one — at the two common spacings, before you add corners, openings and waste. Wall lengths are in feet with the rough metric equivalent; framing at 400 mm or 600 mm on center gives a nearly identical count, usually within one stud.
| Wall length | Studs @ 16 in OC | Studs @ 24 in OC |
|---|---|---|
| 8 ft (≈2.4 m) | 7 | 5 |
| 10 ft (≈3.0 m) | 9 | 6 |
| 12 ft (≈3.6 m) | 10 | 7 |
| 16 ft (≈4.9 m) | 13 | 9 |
| 20 ft (≈6.1 m) | 16 | 11 |
| 24 ft (≈7.3 m) | 19 | 13 |
| 30 ft (≈9.1 m) | 24 | 16 |
| 40 ft (≈12.2 m) | 31 | 21 |
Read it as the starting point, then add your corners, openings and waste on top. The framing calculator folds all of that in for any length and spacing.
4. Choosing the stud spacing
Spacing is the single biggest lever on how much lumber a wall uses, and it is not a free choice. Sixteen inches on center is the workhorse: it is stiff, gives plenty of fastening surface for sheathing and drywall, and is what most load-bearing and many interior walls use. Twenty-four inches on center uses roughly a third less framing and is common for non-load-bearing partitions and for modern “advanced framing,” which pairs the wider spacing with thicker studs and aligned framing to save material and make room for more insulation. Twelve-inch spacing turns up where a wall carries unusually heavy loads.
What you can actually use is governed by your local building code and the load the wall carries, not by preference. The code links the spacing to the stud size, the lumber species and grade, and the height of the wall, and those limits live in published span and stud tables. Frame to the spacing on your approved plans or the one your inspector specifies. If you are weighing the two, switch the calculator between 16 and 24 inches to see the difference in stud count before you order.
5. Corners, openings and the parts that aren't studs
A real wall is more than a row of evenly spaced studs. At each corner, framers add studs so that the inside corner has a surface to screw drywall to — a classic three-stud corner, or a two-stud corner with drywall clips, adds roughly two studs beyond the line stud. Every door and window interrupts the regular spacing: the opening is bordered by full-height king studs, and shorter jack (or trimmer) studs sit inside them to carry the header across the gap. Above and below the opening, short “cripple” studs continue the spacing. Allowing about two extra studs per opening covers the jacks for a typical door or window; a wide opening with a deep built-up header needs more.
Beyond studs, your take-off includes the plates already mentioned, the headers over each opening, and blocking or fire-stops where the code calls for them. Headers in particular are sized from span tables, not guessed — the wider the opening and the heavier the load above, the bigger the header. This guide and the calculator deliberately stay on the counting side of framing; for the structural sizing you will lean on code tables or an engineer, covered in the next section.
6. What this calculator does not do: spans
It is worth being clear about the line between counting and structure. A framing calculator tells you how many pieces to buy; it does not tell you how far a stud, joist or rafter is allowed to span, or how tall a stud wall may be, or what size header a wide opening needs. Those answers come from your local code's span tables and depend on the lumber species and grade, the spacing, and the load — numbers that vary by jurisdiction and that we will not guess here, because a wrong span figure on a structural member is a safety problem, not a rounding error.
Standard 2x4 stud walls up to a normal storey height are routine, but tall walls, load-bearing walls, headers and floor or roof framing must be checked against the published span tables or signed off by an engineer. Use this tool to plan your material order and your budget, and use the official span tables for anything that carries a load. For related quantities, our board foot calculator totals the lumber volume you are buying, the drywall calculator covers the sheets that go over the framing, and the carpentry hub collects the rest of the framing and carpentry tools.
7. Ordering with confidence
Once you have the stud count, round to how lumber is actually sold and stored. Buy a few spare studs beyond the waste allowance if your yard sells in bundles, since the price break is often worth it and straight studs are always useful. Sort as you go: keep the straightest pieces for visible or critical framing and use the slightly bowed ones for blocking and cripples. Check your plate lumber length too — long walls need plate stock joined over a stud, so order full lengths where you can to minimise joints.
Most of all, base the count on the wall in front of you rather than a generic figure. Measure the real length, count the real corners and openings, and pick the spacing your plans call for. The framing calculator turns those measurements into a stud count, a plate length and a total lumber figure in seconds, so your order matches the wall and you are not making a second trip to the yard.
Common questions
- How many studs do I need for a wall?
- studs = (wall length ÷ stud spacing, rounded up) + 1, plus about 2 per corner and 2 per door or window opening, then a small waste allowance. A 20 ft wall at 16 in on-center is 16 studs for the run; add one opening and 10% waste and you'd buy about 20.
- How do you calculate the number of studs?
- Divide the wall length by the spacing and round up for the number of bays, then add one because a stud sits at both ends. Add roughly two extra studs per corner and two per opening, then a waste allowance. The method is identical in imperial or metric — only the spacing figure changes.
- Should wall studs be 16 or 24 inches on center?
- Both are standard. 16 in (about 400 mm) is the most common spacing for load-bearing and most interior walls; 24 in (about 600 mm) saves lumber and suits many non-load-bearing and energy-efficient walls. Your local code and the wall's load decide which is allowed.
- How many studs are in a 10-foot wall?
- A straight 10 ft wall is 9 studs at 16 in on-center, or 6 at 24 in, before extras. Add about 2 per corner and 2 per opening plus waste, so a 10 ft wall with a door is usually around 12 studs.
Reference & education only. Not professional, engineering, or code-compliance advice. Estimates are based on published model codes; local amendments and your Authority Having Jurisdiction (AHJ) govern. Always verify against the current adopted code and a licensed professional before doing work.
Last reviewed 2026-06.