Stud Calculator
This stud calculator works out how many wall studs to buy, plus the top and bottom plates to go with them. Enter your wall length in feet and inches (or meters), pick 16- or 24-inch on-center spacing, and the totals update instantly — including a 10% waste allowance.
Studs needed
16studs
- With 10% waste — buy18 studs
- Plates (1 bottom + 2 top)36 linear ft
- Plate boards5 × 8 ft · 3 × 12 ft · 3 × 16 ft
Formulas last reviewed on .
How the stud count is calculated
The count starts with your wall length divided by the on-center spacing, rounded up, plus one:
plates = 3 × wall length
Dividing length by spacing gives the number of bays between stud centers. Rounding up covers walls that don’t split evenly — a 10-foot wall at 16-inch centers is 7.5 bays, so you frame 8. The +1 is the stud that closes the far end of the wall; without it you’d frame every bay but leave nothing to nail the last sheet of drywall to.
On top of that base count, the calculator adds two studs per corner (a corner needs extra framing to give both intersecting walls a nailing surface) and two studs per opening for the king studs that run full height on each side of a door or window.
Plate stock is a straight 3× the wall length: one bottom plate and the doubled top plate used in standard platform framing. The board counts show how that total splits into 8-, 12-, or 16-foot lumber, always rounding up to whole boards.
Worked example: a 12-foot garage partition wall
Say you’re splitting off a workshop at the back of a garage with a 12-foot partition wall, framed at 16 inches on center, tied into the existing walls at both ends (2 corners), with one door in it. That’s exactly what the calculator loads by default, so you can follow along in the result box above.
- Base count: 12 ft = 144 inches. 144 ÷ 16 = 9 bays, no rounding needed. 9 + 1 = 10 studs.
- Corners: 2 corners × 2 studs = 4 more. Running total: 14.
- Door opening: 1 opening × 2 king studs = 2 more. Total: 16 studs.
- Waste: 16 × 1.10 = 17.6, rounded up to 18 studs to buy. Lumber racks always hide a few twisted or crowned boards, and the spares become jack studs and cripples for the door.
- Plates: 3 × 12 ft = 36 linear feet — five 8-foot boards, or three 12-footers with no cuts at all.
For this wall you’d put 18 studs and three 12-foot plates on the truck. Buy the extra studs — swapping a banana-shaped 2×4 mid-project costs more time than it’s worth.
How many studs do I need for an 8 to 24-foot wall?
The table below covers the common wall lengths at a glance. Counts are for a straight run with both end studs included — add two studs per corner, two per opening, and your 10% waste on top.
| Wall length | Studs @ 16″ OC | Studs @ 24″ OC |
|---|---|---|
| 8 ft | 7 | 5 |
| 10 ft | 9 | 6 |
| 12 ft | 10 | 7 |
| 14 ft | 12 | 8 |
| 16 ft | 13 | 9 |
| 20 ft | 16 | 11 |
| 24 ft | 19 | 13 |
Notice the counts aren’t proportional: a 10-foot wall needs 9 studs at 16-inch centers, not 8, because the last partial bay still needs a full stud. That round-up is where hand estimates most often come up one short.
Frequently asked questions
Should I frame at 16 or 24 inches on center?
Sixteen inches on center is the default for most interior and exterior walls, and it’s what drywall and sheathing sheet sizes assume. Framing at 24 inches on center uses roughly a quarter fewer studs and is permitted for many non-load-bearing walls — and some load-bearing ones under advanced framing rules — but check your local code first. When in doubt, frame at 16: the lumber savings rarely outweigh a failed inspection.
Does the stud count include both ends of the wall?
Yes. The formula rounds the wall length up to a whole number of spacing bays and then adds one, which accounts for the stud at each end. That’s why an 8-foot wall at 16-inch centers needs 7 studs, not 6: studs mark the start of each of the six bays, and the seventh closes the far end of the wall.
How many studs are in an 8-foot section of wall?
A straight 8-foot section framed at 16 inches on center takes 7 studs, counting both ends; at 24 inches on center it takes 5. Those figures are for the section by itself — add two studs for every corner it forms with another wall, and two for each door or window opening in it.
What are king studs and jack studs?
King studs are the full-height studs nailed on each side of a door or window opening, running from bottom plate to top plate. Jack studs (also called trimmers) are shorter studs fastened to the kings that carry the header over the opening directly. This calculator adds the two king studs per opening; jack studs and cripples are typically cut from the waste allowance and offcuts.
What lumber should I use for the top and bottom plates?
Use the same dimension lumber as your studs — 2×4 plates for a 2×4 wall — in the longest straight lengths you can haul, since fewer joints make a straighter wall. Any bottom plate sitting on a concrete slab must be pressure-treated. The calculator totals the full 3× wall length: one bottom plate plus the doubled top plate used in platform framing.
These results are planning estimates only — verify quantities with your supplier and local building code before you buy or build. See our terms of use.