Stud Calculator
Calculate studs, top and bottom plates and headers for any framed wall - by length, height and stud spacing.
The stud calculator returns studs, top and bottom plates and header lumber for any framed wall. Standard residential walls are 8 ft tall with 2x4 studs at 16 inch on-center spacing - this matches drywall sheets (4x8 or 4x12 ft) without unnecessary cuts. 2x6 walls are common for exterior insulated walls in cold climates. 24 inch on-center spacing (advanced framing) saves lumber but requires careful subfloor and sheathing selection. Every door or window opening adds 4 studs on average: a king stud and jack/trimmer stud on each side, plus cripples above the header. Top plates are doubled in load-bearing walls (the second top plate ties walls together at corners).
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Frequently asked questions
At 16 in on-center spacing, a 20 ft wall (240 in) needs 16 field studs (240/16 + 1 starter). Add 4 studs per opening (king + jack each side, plus a few cripples) - a wall with 1 door and 2 windows = 12 extra studs. Plus 3 corner studs. Total: 31 studs. Round up to 35 to allow for cut waste and culled bows.
16 in OC is the residential default - works with all sheathing and subfloor products, allows blocking at every joint, and gives the wall stiffness with single 2x4 studs. 24 in OC (called advanced framing) saves 15-20% on lumber and reduces thermal bridging but requires 1/2 in or thicker drywall to span the wider gap without sagging, and exterior sheathing needs to span 24 in (most OSB and plywood does). Use 24 in OC with 2x6 studs for the best insulation value.
A double top plate is two 2x4s (or 2x6s) stacked at the top of a stud wall, with the joints offset by at least 4 ft between layers. The double plate ties walls together at intersections and corners - the upper plate laps over from one wall onto the next. IRC requires it for any load-bearing wall (most exterior walls and major interior walls). Non-load-bearing interior partitions can use a single top plate.
Standard rule of thumb for non-load-bearing or single-story load-bearing: 2x8 doubled for openings under 4 ft, 2x10 doubled for 4-6 ft openings, 2x12 doubled for 6-8 ft. For two-story load-bearing walls or any large opening, consult a span table (IRC R602.7) or get an engineer's stamp. Headers fill the space between the king studs and rest on the jack studs - they transfer the load above the opening down to the wall framing.
20 ft long, 8 ft tall, 16 in OC, 1 door + 2 windows: 31 2x4 studs (cut to 92-5/8 in for 8 ft wall after plates), 20 ft of bottom plate, 40 ft of double top plate, 12 ft of header lumber. Round up by 10-15% for cut waste and bows. That is about 35 2x4 studs and 5 sticks of 2x4x16 ft plate stock - approximately $400-500 in framing lumber at 2026 prices.