Studs and plates
Framing calculator
Enter each wall run and the stud spacing. This counts the regular layout, adds the extra studs corners and openings need, and works out the plate stock.
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The layout, then everything the layout does not cover
A 40 foot wall at 16 inches on center has 30 spaces and therefore 31 studs — the same off-by-one that catches people on fence posts. Dividing the length by the spacing and stopping there leaves you a stud short on every wall.
Then come the extras the layout does not include: a corner needs a post and backing to catch the drywall on the return, and every opening needs a king stud running full height plus a jack carrying the header, on both sides. Those are counted separately here rather than buried in a percentage.
Studs by spacing on a 40 ft wall
| Spacing | Spaces | Studs | Against 16 in o.c. |
|---|---|---|---|
| 12 in o.c. | 40 | 41 | +10 |
| 16 in o.c. | 30 | 31 | — |
| 24 in o.c. | 20 | 21 | −10 |
Order over, and cull as you go
Framing lumber is graded, not selected. Some of every bundle is bowed, crowned, twisted or split, and you want the freedom to reject a stick rather than fight it into a wall. A few percent over is not waste, it is the ability to say no.
Sight down every stud before it goes in and mark the crown, then put all the crowns the same way. A wall framed with the crowns alternating is wavy before the drywall is even on it.
This counts sticks, it does not size them
What size the studs have to be, how tall a wall can go at a given spacing, what has to be doubled, how big the header over a 6 foot opening needs to be and whether the wall is load bearing at all are structural questions. They are answered by span tables and by your local code, and they depend on what is above the wall.
We do not publish span tables here, for the same reason we do not publish R-values: they are set by whichever code your jurisdiction has adopted and they change on a cycle. Get them from your building department.
Common questions
How many studs do I need for a 40 foot wall?
Thirty-one at 16 inches on center, before corners and openings. The spacing gives you 30 spaces, and a wall needs a stud at both ends.
How many studs for a 10 foot wall at 16 inch centers?
Nine. Ten feet is 120 inches, which is seven and a half spaces at 16 inches: eight studs land on the layout marks and a ninth closes the end of the wall, leaving a short 8 inch bay. Rounding the spaces down and stopping at eight is how you come up a stud short.
How many extra studs does a door or window need?
Four — a king stud and a jack stud on each side. The king runs full height and the jack carries the end of the header.
What is a double top plate?
Two plates stacked at the top of the wall, lapped at the corners and intersections to tie the walls together. With the bottom plate that is three plates deep, so a 40 foot wall takes 120 feet of plate stock.
Is 24 inch stud spacing acceptable?
It is used, and it saves about a third of the studs, but whether it is permitted depends on the load, the stud size and your local code. Check before ordering.
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