Stud Calculator

Q: How do I calculate how many studs I need?

Multiply the wall length in feet by 12, divide by the stud spacing in inches and add one. Then add about two studs for every door or window, two for every corner and two for every wall intersection, and add 10 percent for culls and waste.

Q: How many studs per foot of wall?

A common rule of thumb is one stud per linear foot of wall at 16 inches on center once openings, corners and waste are included. At 24 inches on center it is about three studs for every four feet.

Q: How many studs do I need for a 12 foot wall?

At 16 inches on center, 12 x 12 / 16 + 1 = 10 studs, before adding studs for any openings or corners. At 24 inches on center it is 7.

Q: What length stud do I need for an 8 foot wall?

92 5/8 inch precut studs. With a bottom plate and a double top plate, the framed wall is 97 1/8 inches tall, which leaves room for 8 foot drywall on the walls and the ceiling.

Q: Should studs be 16 or 24 inches on center?

16 inches on center is standard for 2x4 walls. 24 inches on center uses about a quarter fewer studs and is common with 2x6 walls, but it must be allowed by your code and the wall's loads, and the sheathing and drywall must be rated for it.

Q: How many studs are needed for a door or window opening?

Each side gets a full-height king stud and a shorter jack (trimmer) stud that carries the header, so four in total, plus short cripple studs above and below. Because the opening replaces some regular studs, a net extra of about two studs per opening is a good estimate.

Enter your wall length, height and stud spacing to get how many studs to buy. It adds the extras for doors, windows, corners and wall intersections, and also gives plates, header stock, sheathing and board feet.

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Quick answer

Studs = wall length (ft) × 12 ÷ spacing (in) + 1, plus about 2 per opening, 2 per corner and 2 per wall intersection, plus 10%. A 40 ft wall at 16 in on center with 3 openings, 2 corners and 1 intersection needs 31 + 12 = 43 studs, so buy 48, plus 8 plates of 16 ft.

How to use this stud calculator

Enter the wall length. Do one wall at a time, or add every wall together for the whole floor.
Choose the wall height. It sets the precut stud length.
Pick 2×4 or 2×6 and the spacing, 16 or 24 in on center.
Count doors, windows, corners and intersections. Each needs extra studs for king and jack studs or drywall backing.
Read the order: studs, 16 ft plates, header stock, sheathing sheets, board feet and nails.

How many studs for common wall lengths

Wall length	16 in o.c. (no openings)	24 in o.c. (no openings)
8 ft	7	5
10 ft	9	6
12 ft	10	7
16 ft	13	9
20 ft	16	11
24 ft	19	13
40 ft	31	21

The quick rule of thumb is one stud per foot of wall at 16 in on center. That covers openings and corners on a typical wall.

Precut stud lengths by wall height

Precut studs are sized so that one bottom plate and a double top plate (three 1½ in plates) give a wall slightly taller than the drywall.

Ceiling	Precut stud	Framed wall height
8 ft	92⅝ in	97⅛ in
9 ft	104⅝ in	109⅛ in
10 ft	116⅝ in	121⅛ in

What every opening, corner and intersection needs

Doors and windowsA full-height king stud and a jack (trimmer) stud on each side, a header across the top, and short cripple studs above the header and under a window sill.
CornersTwo or three studs, so both walls have a nailing surface for drywall inside the corner.
Wall intersectionsExtra studs or blocking in the through wall where another wall meets it, again for drywall backing.
PlatesOne bottom plate and two top plates, so three times the wall length. Lap the top plates over joints and corners. Use pressure-treated lumber for a bottom plate on concrete.

Header size depends on the opening width and the load above it, so size headers from your local code tables or your plans. The calculator only counts the length of header stock.

Worked example

40 ft wall, 8 ft high, 2×4 at 16 in: 40 × 12 ÷ 16 + 1 = 31 studs
3 openings, 2 corners, 1 intersection: + 12 studs = 43
Add 10% for culls and waste: 48 studs (92⅝ in)
Plates (3 × 40 ft + 5%): 8 × 16 ft 2×4
Sheathing (40 × 8 + 10%): 11 sheets of 4×8

Frequently asked questions

How do I calculate how many studs I need?

Wall length (ft) × 12 ÷ spacing + 1. Add about 2 per opening, 2 per corner and 2 per intersection, then add 10%.

How many studs per foot of wall?

About one per linear foot at 16 in on center once openings, corners and waste are included, or about three per four feet at 24 in.

How many studs do I need for a 12 foot wall?

10 at 16 in on center, or 7 at 24 in, before adding studs for openings and corners.

What length stud do I need for an 8 foot wall?

92⅝ in precut studs. With three plates, the wall frames to 97⅛ in.

Should studs be 16 or 24 inches on center?

16 in is standard for 2×4 walls. 24 in uses about a quarter fewer studs and is common with 2×6, but only where code and loads allow it.

How many studs are needed for a door or window opening?

A king and a jack stud on each side (four in total), plus cripples. That is a net extra of about two studs per opening.

What this calculator assumes

Straight walls with studs at the spacing you choose, a single bottom plate and a double top plate.
About 2 extra studs per opening, corner and intersection. Cripples and blocking come from offcuts.
Header stock is two plies per opening, 3 in longer than the opening. Sheathing is 4×8 sheets with 10% waste.
Load-bearing walls, headers and spacing must meet your local building code.