Wall Stud Calculator
How many studs for a framed wall
Framing a wall? Enter the length to get the stud count at 16 or 24 inch on-centre spacing. Below you'll find how many studs a wall of any length needs, a stud size chart, the plates and extras most estimates forget, and when 24 inch spacing is allowed.
How many studs do I need for a wall?
This stud wall calculator doubles as a wall framing calculator and a wall stud spacing calculator, and the same arithmetic serves as a stud wall timber calculator in the UK or a metal stud calculator, since only the material changes and not the spacing.
The formula is (wall length ÷ spacing) + 1. A 20 ft wall at 16 in on centre is 240 in ÷ 16 = 15, plus one to close the end, so 16 studs in the main run.
That is the straight line of studs and nothing else. Every real wall needs more, and the extras are where estimates go wrong.
Rule of thumb: studs run about 0.75 per linear foot at 16 in centres, or 0.5 per foot at 24 in. Then add the extras below.
Studs per wall length
Main run only, before corners, openings and blocking.
| Wall length | 16 in on centre | 24 in on centre |
|---|---|---|
| 8 ft | 7 studs | 5 studs |
| 10 ft | 9 studs | 6 studs |
| 12 ft | 10 studs | 7 studs |
| 16 ft | 13 studs | 9 studs |
| 20 ft | 16 studs | 11 studs |
| 24 ft | 19 studs | 13 studs |
| 32 ft | 25 studs | 17 studs |
Wall stud size chart
Nominal sizes are not actual sizes. A "2x4" has been 1.5 in × 3.5 in since it was planed, and framing that assumes the nominal figure ends up out by half an inch per member.
| Nominal | Actual | Metric (approx) | Typical use |
|---|---|---|---|
| 2 × 3 | 1.5 × 2.5 in | 38 × 63 mm | Non-load-bearing partitions |
| 2 × 4 | 1.5 × 3.5 in | 38 × 89 mm | Standard interior and exterior walls |
| 2 × 6 | 1.5 × 5.5 in | 38 × 140 mm | Exterior walls needing deeper insulation |
| 2 × 8 | 1.5 × 7.25 in | 38 × 184 mm | Headers, tall walls |
UK stud walls typically use 38 × 63 mm or 38 × 89 mm CLS timber at 400 mm or 600 mm centres, which map closely to 16 in and 24 in. Metal studs come in the same 16 and 24 in spacings but in gauge rather than nominal sizes, and are lighter, straighter and non-combustible, though they need different fixings.
16 or 24 inch spacing?
| Wall | Spacing | Why |
|---|---|---|
| Load-bearing exterior | 16 in | Standard, and required by many codes |
| Interior load-bearing | 16 in | Carries floor or roof above |
| Non-load-bearing partition | 16 or 24 in | 24 saves lumber; 16 feels more solid |
| Advanced framing (2x6) | 24 in | Deeper cavity, less thermal bridging |
| Tile or heavy finish | 16 in | Backer board needs the support |
One practical point that outranks the lumber saving: drywall and sheet goods come in 4 ft widths, which divides evenly by both 16 and 24 in. Anything else and every sheet needs cutting to land on a stud.
Plates, corners and openings
The stud count is roughly half the lumber. Budget for:
- Plates: a single bottom plate and a double top plate, so three wall-length runs.
- Corners: 2 to 3 extra studs each for backing and a nailing surface for drywall.
- Wall intersections: 1 to 2 extra where a partition meets this wall.
- Each opening: 2 king studs, 2 jack studs, a header and cripples above (and below, for a window) — commonly 6 to 8 extra pieces per door or window.
- Blocking: mid-height blocking or fire-blocking where required, plus backing for cabinets, grab rails and TVs.
Worked example: a 20 ft wall with one door
| Item | Working | Pieces |
|---|---|---|
| Main studs, 16 in OC | (240 ÷ 16) + 1 | 16 |
| Corners (two) | 2 × 3 | 6 |
| Door opening | 2 king + 2 jack + cripples | ~6 |
| Plates | 3 runs × 20 ft | 60 linear ft |
| Cull allowance | ~10% | 3 |
| Total studs to buy | — | ~31 |
The bare calculation said 16. The wall actually takes about 31 studs plus 60 ft of plate stock. That gap is why framing orders come up short.
Framing mistakes
- Ordering only the stud-line count. Corners, openings and plates roughly double it.
- Using nominal dimensions. A 2x4 is 1.5 × 3.5 in, not 2 × 4.
- Forgetting the double top plate on load-bearing walls.
- Not culling bowed studs. A crooked stud telegraphs through drywall permanently; use the worst as cripples and blocking.
- Measuring on-centre from the wall end rather than the first stud's edge, which throws every sheet joint off the stud.
- 24 in spacing under tile backer board, which needs 16.
How this wall stud calculator works out its numbers
Stud count is wall length ÷ spacing, plus one to finish the run. At 16 in on centre that is one stud every 1.333 ft; at 24 in it is one every 2 ft.
- This is the bare stud line only. Plates, corners, openings and blocking are described on the page rather than folded silently into the number, because they vary too much by wall to estimate blindly.
- Spacing rules reflect common residential practice in the US and UK. Load-bearing requirements are set by your local building code, which overrides anything here.
Figures reviewed . Every worked example on this page is checked against the calculator above.
Wall Stud Calculator: frequently asked questions
How many studs do I need for a wall?
(Wall length in inches ÷ spacing) + 1 for the main run. A 20 ft wall at 16 in on centre is 16 studs. Then add roughly 3 per corner, 6 to 8 per door or window, and three wall-length runs of plate stock.
How many studs in a 10 foot wall?
Nine at 16 in on centre, or six at 24 in, for the main run. Add corners, openings and plates on top; a real 10 ft wall with one opening usually takes 15 to 18 pieces.
How many studs in a 20 foot wall?
Sixteen at 16 in on centre, or eleven at 24 in. With two corners, one door and a 10% cull allowance the realistic order is about 31 studs plus 60 linear feet of plate stock.
Is 16 or 24 inch stud spacing better?
16 in is standard for load-bearing and exterior walls and is required by many codes. 24 in saves lumber on non-load-bearing partitions and suits 2x6 advanced framing. Use 16 in under tile backer board.
What size is a wall stud actually?
A nominal 2x4 measures 1.5 by 3.5 inches, and a 2x6 is 1.5 by 5.5. UK stud walls typically use 38 x 63 mm or 38 x 89 mm CLS timber at 400 or 600 mm centres, which correspond closely to 16 and 24 inches.
How much extra lumber should I buy for framing?
Add about 10 to 15% on the stud count for boards you will cull as too bowed, plus the plates, corner studs and opening framing. The bare stud line is typically only half the total lumber.
Can I use metal studs instead of timber?
Yes, at the same 16 and 24 inch spacings. Metal studs are lighter, straighter and non-combustible, and are common in commercial partitions, but they need different fixings and are less straightforward for hanging heavy items without backing.