Framing Calculator
Find how many studs and plates to buy for wood-framed walls. This stud calculator counts the studs on each wall at your stud spacing, adds studs for corners, wall intersections, and doors and windows, and works out the stud length and the top and bottom plates.
- Choose US or Metric. You can still change the unit of any single field.
- Enter the length of each straight wall, measured end to end, and use Add wall for the next one.
- Enter the Wall height, from the bottom of the bottom plate to the top of the top plate. For walls of different heights, work out each height separately. For a sloped wall, such as a gable end, enter the height at its tallest point: the number of studs is the same, and the stud lengths come out long.
- Choose the Stud spacing, or choose Custom spacing for a spacing that isn't listed, such as 19.2 in.
- Enter the number of Corners, Wall intersections, and Doors and windows. Leave a field blank if there are none.
- Under Framing details, choose the top plate and check the plate thickness and the stock lengths. The extra studs for each corner, intersection, and opening start at the defaults below, and you can change them to match how you frame: doors in non-bearing partitions need fewer, and wide openings need the number on your plans.
- Optionally, enter a price per stud and a plate price, per board or by length, to estimate the cost.
Length fields accept whole numbers, decimals, fractions, and mixed
numbers, such as 12, 10.5, 3/4, or
92 5/8. Choose ft + in as the unit to enter a
length such as 8 ft 1 1/8 in in two fields.
How to calculate studs and plates
Each wall gets a stud at both ends and studs in between, no farther apart than the stud spacing, center to center:
Studs per wall = wall length ÷ stud spacing, rounded up, + 1
Extra studs = corners × extra per corner + intersections × extra per intersection + openings × extra per opening
Studs needed = (studs on all walls + extra studs) × (1 + waste % ÷ 100), rounded up
The calculator counts each wall on its own, because every wall needs its own end studs. Four walls of 12, 10, 12, and 10 ft at 16 in need 10 + 9 + 10 + 9 = 38 studs, while 44 ft divided at once gives only 34.
Stud length
Stud length = wall height − plates × plate thickness
Studs to buy = studs needed ÷ studs cut from each stock length, rounded up
A wall has one bottom plate and a double or single top plate, so there are 3 or 2 plates. When the stud length is half the stock length or less, the calculator cuts two or more studs from each stock length. When a stud is longer than the stock length, it asks for a longer stock length.
Plates
Plate length = total wall length × plates × (1 + waste % ÷ 100)
Plates to buy = plate length ÷ plate stock length, rounded up
Plates run the full length of every wall, and the offcut from one wall is used on another wall or another layer. The waste allowance applies to both the studs and the plates.
Stud spacing, extra studs, and plates
Stud spacing
In the US, 16 in on center is the most common spacing. Building Science Corporation's BSI-030: Advanced Framing describes a 2x4 wall at 16-inch centers as the standard wall, and advanced framing at 24 in. As an example from the US code, IRC Table R602.3(5) allows 2x4 bearing studs at up to 24 in when they carry only a roof and ceiling, 16 in when they also carry one floor, and 24 in for non-bearing walls. The right spacing depends on the loads and the wall covering, so use the spacing on your plans and check the code where you build. The calculator doesn't check your spacing.
In Metric, CMHC's Canadian Wood-Frame House Construction gives 400 mm as the common spacing, the same as 16 in, with 300 or 600 mm in some walls. UK timber merchant Harlow Bros lists 400 and 600 mm, and 450 mm in some tiled rooms. RMIT University's building guide gives 450 or 600 mm in Australia, with 450 mm under tiled roofs, so the calculator starts at 450 mm there and at 400 mm elsewhere.
Extra studs
The defaults add 1 stud at each corner and 2 at each wall intersection, which with the wall end studs makes the three-stud posts CMHC describes as usual at corners and intersections. Each door or window adds 4: a full-length king stud and a jack stud under the header on each side.
- For two-stud corners, or intersections tied with blocking or metal clips as in BSI-030's advanced framing, set the corner and intersection extras to 0. If you hang headers on metal hangers instead of jack studs, set the opening extra to 2.
- Doors in non-bearing partitions can use single studs on each side, so they need fewer extra studs.
- Openings wider than 3 m (10 ft) take double jack studs on each side, so set the opening extra to 6. In exterior walls, IRC Table R602.7.5 can call for more king studs at wide openings, so use the number on your plans.
The layout studs that fall inside a door or window are not taken off. They become the short cripple studs above and below the opening.
Plates and stock lengths
IRC R602.3.2 calls for a double top plate, and allows a single top plate when the rafters or joists above sit within 1 in of the center of the studs. With a single top plate, the studs are one plate thickness longer. Joints in plates don't have to land on a stud, which is why offcuts can be reused. Joints in the two top plates are offset at least 24 in, and the waste allowance covers that and the short offcuts. Enter longer boards, such as 12 or 16 ft, for fewer joints.
Precut studs of 92 5/8 in are sold for 8 ft walls: with a bottom plate and two top plates of 1 1/2 in, the wall is 97 1/8 in tall. For 9 ft and 10 ft ceilings, enter 104 5/8 in or 116 5/8 in precuts. In the UK, CLS studwork timber is 38 × 89 mm and comes in lengths such as 2.4, 3.0, and 4.8 m. If your plates are a different thickness, enter the actual thickness of the timber you use.
The 10% waste allowance is the most that the LEED for Homes framing order waste factor allows. Raise it for lumber with many warped or split pieces.
Examples
A 12 × 10 ft room
Walls of 12, 10, 12, and 10 ft at 16 in need 38 studs. With 4 corners, a door, and a window, add 4 + 8 = 12 extra studs for 50, and 10% waste makes 55 studs. For walls 97 1/8 in tall, each stud is 92 5/8 in, so you buy 55 precut studs. The plates are 44 × 3 = 132 ft, plus 10% is 145.2 ft, or 19 boards of 8 ft (10 boards of 16 ft). At $4.25 per stud and $5.10 per plate, the cost is $330.65.
A short wall
A 20 ft wall 4 ft tall needs 16 studs, or 18 with 10% waste. Each stud is 43 1/2 in, so you can cut 2 from each 92 5/8 in stud and buy 9 studs.
A Metric room
Walls of 4, 3, 4, and 3 m at 400 mm need 40 studs. With 4 corners and one door, add 8 for 48, and 10% waste makes 53 studs. For walls 2.4 m tall with 38 mm plates, each stud is 2,286 mm and fits in a 2.4 m length. The plates are 46.2 m with waste, or 20 lengths of 2.4 m. At 450 mm spacing, the same room needs 49 studs.
FAQ
For a 12 ft wall at 16 in on center, 10: 144 ÷ 16 = 9 spaces, plus 1 for the stud at the far end. Add studs for corners, intersections, and openings, and a waste allowance.
About 55, with 4 corners, a door, a window, and 10% waste: 38 studs along the walls at 16 in, plus 12 extra studs, makes 50.
92 5/8 in precut studs, the length sold for 8 ft walls. With a bottom plate and a double top plate of 1 1/2 in each, the wall is 97 1/8 in tall. For 9 ft ceilings, use 104 5/8 in studs.
Three times the wall length with a double top plate, or twice with a single top plate. For 44 ft of walls, that is 132 ft, or 145.2 ft with 10% waste, which is 19 boards of 8 ft.
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