How Many Studs in a 40 Foot Wall?
Studs to buy
39 studs
40 ft of wall, 8 ft tall, 16 in on center, 2 corners, no openings, 10 % waste.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Wall length40 ft
- Wall height8 ft
- Stud spacing16 in on center
- Doors and windows0 openings
- Average opening width3.5 ft
- Corners2 count
- Partition intersections0 count
- Waste allowance10 %
Studs to buy39 studs
| Wall area | 320 sq ft |
|---|---|
| Field studs | 31at 16 in on center |
| Positions the openings remove | 0 |
| Cripples above and below | 0 |
| Corners and tees | 4two extra at each |
| Kings and jacks | 0four per opening |
| Studs before waste | 35 |
| Rule of thumb check | 40one stud per foot of wall |
| Plate stock | 120 ft8 at 16 ft, bottom plate and double top |
| Header stock | 0 fttwo plies, opening plus 6 in of bearing |
| Sheathing | 10 sheets4 by 8, gross wall, no openings taken off |
The material list this produces
| Studs at 8 ft | 39 |
|---|---|
| Plate stock, 16 ft lengths | 8 |
| Sheathing, 4x8 sheets | 10 |
| 16d framing nails, lb | 7 |
Wall length compared
The long end. The middle column is the one stud per foot rule of thumb, and this is where it crosses over: it is a little low at the top of the table, exactly right at 30 ft, and steadily too high after that.
| Wall length | Studs to buy | Rule of thumb check | Plate stock |
|---|---|---|---|
| 20 ft | 22 studs | 20 | 60 ft |
| 30 ft | 30 studs | 30 | 90 ft |
| 40 ft | 39 studs | 40 | 120 ft |
| 50 ft | 47 studs | 50 | 150 ft |
| 60 ft | 55 studs | 60 | 180 ft |
| 70 ft | 63 studs | 70 | 210 ft |
What else matters here
Thirty nine studs, and this is the length where the one stud per foot rule finally stops being useful in the direction people expect.
On a short wall the rule is much too low, because the corner studs are a fixed four however short the wall is. As the wall gets longer those four stop mattering and the field spacing takes over, and since 16 in on center puts a stud every foot and a third rather than every foot, the rule overshoots. At 30 ft the two happen to cross and the rule is exactly right. Here at 40 ft it says 40 and the honest answer is 39. At 70 ft it says 70 and the answer is 63, which is seven studs of fresh air.
A wall this long is also not one wall in practice. It is built and stood in sections, because a 40 ft framed wall with sheathing on it is not liftable, and the sections have to break on a stud with the top plates lapping across the joint to tie them together. That lap is what makes a row of separate walls behave as one, and it is the reason the doubled top plate exists at all. 120 ft of plate stock is what it takes, three feet for every foot of wall.
What this calculator assumes
- Studs are counted position by position: the field studs at your spacing, minus the positions the openings take out, plus the cripples that go back above and below them, plus two extra at every corner and every partition tee, plus a king and a jack on each side of every opening.
- A corner is counted as three studs and a partition tee as three, which is the traditional way. A California corner or a ladder tee uses two plus blocking and saves a stud at each one.
- Cripples are counted as whole studs because they are cut from stock. If you are nesting cuts carefully you will use fewer, and the waste line is where that shows up.
- Plates are one bottom plate and a double top plate, so three times the wall length, and they are priced in 16 ft lengths.
- Headers are figured two plies deep at the opening width plus six inches of bearing. Span, load and species decide the header depth, and that is an engineering question rather than a takeoff one.
- The rule of thumb line is the old one stud per foot of wall at 16 inches on center. It is there as a sanity check, not as the answer.
Questions people ask
How many studs in a 40 foot wall?
39 at 16 in on center, including a ten percent waste allowance, with 120 ft of plate stock and 10 sheets of sheathing.
Is one stud per foot a good rule?
Only at around 30 ft, where it happens to be exact. It is well under on short walls because of the corner studs, and steadily over on long ones because 16 in on center is a stud every foot and a third.
Do I build a 40 foot wall in one piece?
No. It is framed and stood in sections that break over a stud, and the doubled top plate laps across each joint to tie the sections together.
The framing calculator takes any dimensions you like and hands back the same list.