Stud Calculator
How many studs for a wall at 16 or 24 in on centre, plus corner and T-intersection studs, king and jack studs, cripples, plates and the precut stud length.
Stud Calculator: with the default inputs, studs to buy is 62.
Add up every wall you are framing. Corners and tees are counted separately below.
Each separate run gets one extra stud, because a run has a stud at both ends.
Subfloor to the top of the top plate. The precut stud length is this minus the plates.
IRC Table R602.3(5) allows 24 in on centre for most 2×4 and 2×6 bearing walls; drywall on a 24 in ceiling or wall needs ⅝ in board or a stiffer finish.
Outside or inside corners where two walls meet.
Partitions butting into the middle of a wall.
Rough opening, not the door slab — usually the door width plus 2 in.
Every stud below, plus the waste percentage, rounded up.
- Layout (field) studs
- 16ceil(length ÷ spacing) + 1 per wall run — one at each end and one on every layout mark between.
- Corner studs
- 8
- T-intersection studs
- 0
- King studs
- 6Two full-height studs per opening, one each side of the header.
- Jack (trimmer) studs
- 6Carry the header; cut to the rough opening height.
- Cripple studs
- 20Short studs over every header and under every window sill, on the same layout as the wall.
- Studs before waste
- 56
- Precut stud length
- 91.5 inWall height minus the bottom plate and the top plates, at 1½ in each.
- Stud length in inches and sixteenths
- 91 1/2 in
- Plate stock needed
- 60 ftWall length × (1 bottom plate + your top plates).
- Plate boards
- 4Rounded up at the board length you chose; does not optimise the cut list.
- Total linear feet of lumber
- 537 ftStuds × stud length + plate stock.
- Lumber cost
- $0.00
Assumptions
- Nominal 2× lumber is 1½ in thick dressed (NIST PS 20), so three plates take 4½ in off the framed height.
- Layout studs that fall inside an opening are not deducted; those positions become cripples and the count stays on the safe side.
- Cripple counts assume the opening crosses at most ceil(width ÷ spacing) + 1 layout marks — the maximum, not the average.
- Plate boards are counted at the full board length without optimising the cut list, so a long wall may need one fewer if you plan the splices.
- Nothing here sizes a header, a bearing wall or a stud for load; that is IRC R602.7 and the span tables.
- Every count rounds up.
| Wall length | 12 in o.c. | 16 in o.c. | 19.2 in o.c. | 24 in o.c. |
|---|---|---|---|---|
| 4 ft | 5 | 4 | 4 | 3 |
| 6 ft | 7 | 6 | 5 | 4 |
| 8 ft | 9 | 7 | 6 | 5 |
| 10 ft | 11 | 9 | 8 | 6 |
| 12 ft | 13 | 10 | 9 | 7 |
| 14 ft | 15 | 12 | 10 | 8 |
| 16 ft | 17 | 13 | 11 | 9 |
| 20 ft | 21 | 16 | 14 | 11 |
| 24 ft | 25 | 19 | 16 | 13 |
| 30 ft | 31 | 24 | 20 | 16 |
| 40 ft | 41 | 31 | 26 | 21 |
| 50 ft | 51 | 39 | 33 | 26 |
Layout studs only, for a single run with a stud at each end. Corners, tees, openings and waste are on top.
| Stud | Mark the near edge at | Centre lands at |
|---|---|---|
| 2 | 15 1/4 in | 16 in |
| 3 | 31 1/4 in | 32 in |
| 4 | 47 1/4 in | 48 in |
| 5 | 63 1/4 in | 64 in |
| 6 | 79 1/4 in | 80 in |
| 7 | 95 1/4 in | 96 in |
| 8 | 111 1/4 in | 112 in |
| 9 | 127 1/4 in | 128 in |
| 10 | 143 1/4 in | 144 in |
| 11 | 159 1/4 in | 160 in |
| 12 | 175 1/4 in | 176 in |
| 13 | 191 1/4 in | 192 in |
Stud 1 sits flush with the end of the wall. Pull the first mark back ¾ in — half a 1½ in stud — so the centre lands on the spacing and a 4 ft sheet breaks on a stud. Marks past 200 are not listed.
How this is worked out
The formula
Layout studs = ceil(wall length ÷ spacing) + number of wall runs Corner studs = corners × 2 (three-stud corner) or × 1 (two-stud corner) T-intersection studs = tees × 2 (or 0 with ladder blocking) King studs = openings × 2 Jack studs = openings × jacks per side × 2 Cripples = per door ceil(width ÷ spacing) + 1; per window twice that (over the header and under the sill) Studs to buy = ceil(all of the above × (1 + waste)) Precut stud length = wall height − 1.5 in × (1 bottom plate + top plates) Plate stock = wall length × (1 + top plates)
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Total wall length
- Add up every wall you are framing. Corners and tees are counted separately below.in ft, in, m, cm · 0 or more · defaults to 20
- Number of separate walls
- Each separate run gets one extra stud, because a run has a stud at both ends.from 1 to 500 · whole numbers only · defaults to 1
- Wall height (framed)
- Subfloor to the top of the top plate. The precut stud length is this minus the plates.in ft, in, m, cm · 0 or more · defaults to 8
- Stud spacing
- IRC Table R602.3(5) allows 24 in on centre for most 2×4 and 2×6 bearing walls; drywall on a 24 in ceiling or wall needs ⅝ in board or a stiffer finish.12 in on centre · 16 in on centre (standard) · 19.2 in on centre (5 per 8 ft) · 24 in on centre (advanced framing)
- Corner detail
- Choose one of 3 options.Three-stud corner (adds 2 studs) · Two-stud corner with drywall clips (adds 1) · No extra corner studs
- Corners
- Outside or inside corners where two walls meet.from 0 to 500 · whole numbers only · defaults to 4
- T-intersection detail
- Choose one of 2 options.Two backing studs (adds 2) · Ladder blocking (adds 0 studs)
- T-intersections
- Partitions butting into the middle of a wall.from 0 to 500 · whole numbers only · defaults to 0
- Doors
- A number.from 0 to 500 · whole numbers only · defaults to 1
- Rough opening width per door
- Rough opening, not the door slab — usually the door width plus 2 in.in in, ft, cm, mm, m · 0 or more · defaults to 36
- Windows
- A number.from 0 to 500 · whole numbers only · defaults to 2
- Rough opening width per window
- A number.in in, ft, cm, mm, m · 0 or more · defaults to 36
- Jack (trimmer) studs per side(under More options)
- One per side is typical up to about a 6 ft header span; wider headers usually want two. Check the header table in IRC R602.7.from 0 to 6 · whole numbers only · defaults to 1
- Top plates(under More options)
- IRC R602.3.2 requires a double top plate on a bearing wall unless the single-plate exception is met.from 1 to 3 · whole numbers only · defaults to 2
- Plate board length(under More options)
- Choose one of 5 options.8 ft · 10 ft · 12 ft · 14 ft · 16 ft
- Extra for crooked stock and mistakes(under More options)
- Applied to the stud count only. 10% covers the crowned and twisted boards you cull off the pile.a percentage · from 0 to 100 · defaults to 10
- Price per stud(under More options)
- Leave 0 to skip the cost.in dollars · 0 or more · defaults to 0
- Price per plate board(under More options)
- A number.in dollars · 0 or more · defaults to 0
What you get back
- Studs to buymain answer
- Every stud below, plus the waste percentage, rounded up.
- Layout (field) studs
- ceil(length ÷ spacing) + 1 per wall run — one at each end and one on every layout mark between.
- Corner studs
- T-intersection studs
- King studs
- Two full-height studs per opening, one each side of the header.
- Jack (trimmer) studs
- Carry the header; cut to the rough opening height.
- Cripple studs
- Short studs over every header and under every window sill, on the same layout as the wall.
- Studs before waste
- Precut stud length
- Wall height minus the bottom plate and the top plates, at 1½ in each.
- Stud length in inches and sixteenths
- Plate stock needed
- Wall length × (1 bottom plate + your top plates).
- Plate boards
- Rounded up at the board length you chose; does not optimise the cut list.
- Total linear feet of lumber
- Studs × stud length + plate stock.
- Lumber cost
What this assumes
- Nominal 2× lumber is 1½ in thick dressed (NIST PS 20), so three plates take 4½ in off the framed height.
- Layout studs that fall inside an opening are not deducted; those positions become cripples and the count stays on the safe side.
- Cripple counts assume the opening crosses at most ceil(width ÷ spacing) + 1 layout marks — the maximum, not the average.
- Plate boards are counted at the full board length without optimising the cut list, so a long wall may need one fewer if you plan the splices.
- Nothing here sizes a header, a bearing wall or a stud for load; that is IRC R602.7 and the span tables.
- Every count rounds up.
About this calculator
The stud count for a wall is almost wall length ÷ spacing, and the "almost" is where framing orders go wrong. The layout needs a stud at both ends, so a run is one more than the divisions. Corners and T-intersections need extra studs that are not on the layout at all. Every opening takes two king studs plus jacks, and gives back cripples over the header and under the sill. This counts all of it.
Layout, and the ¾ in you pull back
The first stud sits flush with the end of the wall. After that the marks go on at the spacing — but you pull the tape back half a stud thickness, so the mark is at 15¼ in and the stud's centre lands on 16 in. That is the whole point of "on centre": a 4 ft sheet of plywood or drywall has to break on the middle of a stud, not the edge of one, and it only does that if the centres are on 16, 32, 48 and so on. The layout table lists both numbers for your wall.
16 or 24 on centre
IRC Table R602.3(5) allows 24 in on centre for most 2×4 and 2×6 bearing walls, and going to 24 drops the stud count by about a third — that is the "advanced framing" saving. Two things to know before you do it: ½ in drywall visibly sags between 24 in studs on a ceiling (⅝ in or a resilient finish fixes it), and siding and sheathing schedules sometimes assume 16. The chart compares your own wall at all four spacings.
Openings
- King studs run full height, one on each side of the opening.
- Jack (trimmer) studs are cut to the rough-opening height and carry the header. One per side is normal up to about a 6 ft span; wider headers usually want two. The header table in IRC R602.7 is what decides it.
- Cripples fill above every header and below every window sill, on the wall's own layout.
Layout studs that fall inside an opening are not deducted. That is deliberate: those positions become cripples, the offcuts rarely make a second cripple, and a framing order is much better one stud long than one stud short. It does mean the count is generous on a wall that is mostly glass, and you will get a warning when that happens.
Plates and stud length
Plate stock is the wall length times one bottom plate plus your top plates — normally three lengths of the wall, because IRC R602.3.2 wants a double top plate on a bearing wall. The precut stud length is the framed height minus those three 1½ in plates, which is why the pre-cut stud sold for an “8 ft” wall is 92⅝ in rather than 8 ft: 92⅝ plus three 1½ in plates frames at 97⅛ in, and two stacked 4 ft sheets of drywall come to 96 in with a little clearance left at the floor.
Counts round up — studs, cripples, plate boards, all of them.
Frequently asked questions
▸How many studs do I need for a 20 ft wall at 16 in on centre?
20 ft is 240 in; 240 ÷ 16 is 15, plus one for the stud at the far end, so 16 layout studs. Corners, openings and waste go on top of that.
▸Why is the first layout mark at 15¼ in and not 16?
So the stud's centre lands on 16 in. You pull back half the 1½ in stud thickness, which puts the near edge at 15¼ and the centre at 16 — and that is what lets a 48 in sheet break on the middle of a stud.
▸How many studs are in a corner?
Three in the traditional corner: the end stud of one wall plus two more to give the inside wall something to nail drywall to. A two-stud 'California' corner with drywall clips does the same job with one fewer stud and room for insulation.
▸Is 24 in on centre allowed?
For most 2×4 and 2×6 bearing walls, yes — IRC Table R602.3(5) sets the limits by stud size, wall height and what the wall carries. Use ⅝ in drywall on 24 in framing, especially on ceilings, and check that your sheathing and siding schedules are not written for 16.
▸How long should the studs be for an 8 ft wall?
92⅝ in, the standard precut. The framed height of 97⅛ in less three 1½ in plates (one bottom, two top) leaves 92⅝, and two stacked 4 ft sheets of drywall come to 96 in with a little clearance at the floor.
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