Stud Calculator
A 20-foot wall framed at 16 inches on center needs about 16 studs for the field, plus extras for corners and openings, and 60 feet of plate lumber for the top and bottom. Enter your wall length, height, stud spacing, and the number of corners and openings to get an accurate stud and plate count. The calculator adds a starter stud and doubles up at each corner and opening to match standard residential framing practice.
Quick answer
Stud count is based on the wall length divided by on-center spacing, plus one starter stud.
What this tells you
- •Stud count is based on the wall length divided by on-center spacing, plus one starter stud.
- •Corners and openings each add two extra studs (king and trimmer pairs or corner assemblies).
- •Plates are calculated as three runs of the wall length: one sole plate and a doubled top plate.
How to Use
- 1Enter the total wall length in feet.
- 2Enter the wall height in feet (8 ft is standard for most residential walls).
- 3Select your stud spacing: 12, 16, or 24 inches on center.
- 4Add the number of corners and door/window openings that need extra framing.
- 5Click Calculate to see total studs, plate lumber, and stud lumber needed.
How It Works
Formula
Field Studs = ceil(Wall Length(ft) x 12 / Spacing(in)) + 1
Total Studs = Field Studs + (Corners x 2) + (Openings x 2)
Plate Lumber = Wall Length x 3
Stud Lumber = Total Studs x Wall HeightThe field stud count divides the wall length (in inches) by the on-center spacing and rounds up, then adds one for the starting stud. Extra studs are added in pairs for each corner assembly and each door or window opening (king stud plus trimmer). Plate lumber assumes one sole plate and a doubled top plate, giving three plate lengths per wall.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
20-foot exterior wall with corners and a window
Field studs: ceil(240 / 16) + 1 = 16. Add 4 for corners and 2 for the opening. Total studs = 22. Three plates at 20 ft = 60 ft. Stud lumber = 22 x 8 = 176 linear feet.
12-foot interior partition at 24 OC
Field studs: ceil(144 / 24) + 1 = 7. Add 2 for the doorway opening. Total studs = 9. Plates = 12 x 3 = 36 ft. Stud lumber = 9 x 8 = 72 ft.
Studs Needed by Wall Length (16 OC vs 24 OC)
Field stud counts for common wall lengths at standard on-center spacings. These numbers do not include extras for corners or openings.
| Wall Length (ft) | Studs at 16 OC | Studs at 24 OC |
|---|---|---|
| 8 | 7 | 5 |
| 10 | 9 | 6 |
| 12 | 10 | 7 |
| 16 | 13 | 9 |
| 20 | 16 | 11 |
| 24 | 19 | 13 |
Add 2 studs for each corner and 2 for each door or window opening on top of these field counts.
16 vs 24 Inch On-Center Framing: When to Use Each
Most residential building codes require 16-inch on-center stud spacing for exterior walls and load-bearing interior walls. This spacing gives the wall enough strength to carry roof and floor loads, and it lines up with standard 4x8 sheathing and drywall panels.
Non-load-bearing interior partition walls can sometimes be framed at 24 inches on center, which uses fewer studs and saves on lumber costs. Check your local code before choosing 24 OC, because some jurisdictions require 16 OC everywhere regardless of load path.
For walls taller than 8 feet or walls in high-wind or seismic zones, codes often mandate 16 OC or even 12 OC spacing. When in doubt, frame at 16 OC. The extra lumber cost is small compared to the cost of failing an inspection or weakening the structure.
Common mistakes
- Forgetting to add extra studs for corners and openings, leading to a short lumber order
- Counting the gaps between studs instead of the on-center marks, which underestimates by one stud per wall
- Not ordering plate lumber (sole plate and double top plate), which adds three full wall lengths of material
- Using 24-inch spacing on a load-bearing wall without checking local code requirements