Wall Framing Calculator
Count the studs and plates you need to frame a wall. Enter the wall length and stud spacing, add corners and openings, and this wall framing calculator shows how many studs and plate boards to buy, with a waste allowance for bad boards and miscuts.
Your results will appear here.
How to use the wall framing calculator
- Enter the wall length in feet and inches. Run the calculator once for each wall.
- Choose the stud spacing. 16 in on center is the most common. Some walls can use 24 in on center when the code and the loads allow it.
- Count corners and tie-ins. Each corner or place where another wall meets this one needs extra studs for backing.
- Count doors and windows. Each opening needs king and jack studs on both sides.
- Choose the top plate and plate board length, then set the waste allowance. About 10% extra studs is common.
Stud count formula
Layout studs = Wall length (in) ÷ Spacing (in), rounded down, + 1, plus 1 more if the last space is short
Extra studs = 2 per corner or tie-in + 2 per opening
Studs to buy = (Layout studs + Extra studs) × (1 + Waste %), rounded up
Plate boards = Boards per row × 3 rows (bottom plate + double top plate)
Worked example
A 20 ft wall framed at 16 in on center, with 2 corners, 1 window, a double top plate, 12 ft plate boards and 10% waste:
- Layout studs: 240 ÷ 16 = 15, + 1 = 16 studs
- Extra studs: 2 corners × 2 + 1 opening × 2 = 6 studs
- Studs to buy: 22 × 1.10 = 24.2, rounded up to 25 studs
- Plates: 20 ft needs 2 boards of 12 ft per row × 3 rows = 6 plate boards (60 linear ft)
A shorter 12 ft 6 in wall at 16 in on center has 9 full spaces and a short one, so it needs 11 layout studs.
Studs needed by wall length
| Wall length | Layout studs at 16 in | Layout studs at 24 in |
|---|---|---|
| 8 ft | 7 | 5 |
| 10 ft | 9 | 6 |
| 12 ft | 10 | 7 |
| 16 ft | 13 | 9 |
| 20 ft | 16 | 11 |
| 24 ft | 19 | 13 |
These counts include a stud at each end of the wall, but not the extra studs for corners, openings or waste.
Spacing and plate rules
The International Residential Code sets stud size, height and spacing in Table R602.3(5). For example, 2×4 bearing studs can be spaced up to 24 in on center when they support only a roof and ceiling, but no more than 16 in when they also support a floor above. Bearing and exterior walls normally get a double top plate with joints offset at least 24 in (section R602.3.2). Your local building department has the final say.
What the calculator does not include
- Headers: the beams over doors and windows. Their size depends on the opening width and the load above, so size them from your local code tables.
- Cripple studs: the short studs above headers and below window sills. They can often be cut from offcuts and waste studs.
- Blocking and fire blocking: needed in some walls by code, and for cabinets, grab bars and TVs.
- Sheathing and fasteners: plywood or OSB, nails and anchors are estimated separately.
If your walls are taller than about 8 ft, buy precut studs or longer lumber sized for your ceiling height.
Frequently asked questions
How many studs do I need for a 10 ft wall?
At 16 in on center, a 10 ft wall needs 9 layout studs, including one at each end. Add about 2 for each corner or opening and about 10% for waste.
How do I calculate studs at 16 inches on center?
Divide the wall length in inches by 16, round down, and add 1 for the first stud. If the last space is shorter than 16 in, add one more stud to close the wall.
How many extra studs do I need for a window?
An opening needs a king stud and a jack stud on each side, which is four studs. Because the opening also replaces some regular layout studs, about two extra studs per opening is a common estimate, plus cripples above and below.
Do I need a double top plate?
Bearing walls and exterior walls normally need a double top plate under the International Residential Code. A single top plate is allowed only in specific cases, such as when the framing above lines up with the studs and the joints are tied together.
Can I frame walls at 24 inches on center?
Sometimes. It depends on the stud size, wall height and what the wall supports. Check Table R602.3(5) of the code and your local requirements before you frame at 24 in.
Sources and methodology
The formulas on this page were written and checked by the HomeQuantly Team against the worked examples shown above. Results are estimates for planning; always confirm measurements on site before you buy materials.