Framing Calculator

How to calculate wall framing

A framed wall is a row of studs between a bottom plate and a top plate, with extra pieces around each opening. You count the pieces in groups. The calculator treats the wall as one straight run with a stud at each end:

The 1 1/2 in is the real thickness of dry lumber of 2 in nominal thickness, from the American Softwood Lumber Standard, PS 20-25 (table 3, checked October 2026). The real width of a 2x4 is 3 1/2 in and of a 2x6 is 5 1/2 in, so the plates and studs are thinner than their names.

The exact number of layout studs an opening replaces, and of cripples that fit above it, depends on where the studs fall along the wall. The calculator takes the least number of studs an opening can replace and the most number of cripples that can fit. That way it never comes up short, and it may leave you with one stud too many.

Example: a 20 ft wall with a door and a window

The wall is 20 ft long and 8 ft high, with studs 16 in on center. It has two corners with 3 studs each, one 36 in door and one 48 in window. Each opening has 1 king stud and 1 jack stud per side and a header made of 2 pieces. The plates are two top layers and one bottom plate cut from 12 ft boards. These are the values already in the calculator.

The jack studs, the cripples, the headers and the sill are shorter than the full-height studs, so a lumber order for them is made of shorter pieces. To turn those pieces into boards of the lengths you can buy, type them into the lumber calculator.

Studs by wall length

This is the layout stud count of a plain wall with no openings and no extra corner studs, from the rule wall length in inches ÷ spacing, rounded up, plus 1.

What the code says about stud spacing

Whether you can use 16 in or 24 in depends on the stud size, the wall height and what the wall holds up. The IRC covers it in table R602.3(5), size, height and spacing of wood studs. We read it in the California Residential Code 2025, which is based on the IRC, and in the 2012 IRC as published by Seattle, in October 2026. The values were the same. The table below is a summary of the maximum spacing in inches. A dash means the table has no value.

The table has one more column, for a bearing wall that supports one floor only, and its maximum spacing is 24 in for every size from 2×4 to 2×6. In the same table the unsupported height of a stud in a bearing wall is 10 ft for every size that has a bearing value. The 2×3 is not for exterior walls, and a habitable attic on 2×4 studs is limited to a roof span of 32 ft. Bearing walls must be sheathed on at least one side or have bridging, and the table has other conditions in its notes, so read the whole table in your code before you rely on a spacing.

Corners, top plates and openings

• Corners. The 2025 California Building Code, in its conventional light-frame provisions, says not less than three studs at each corner of an exterior wall, and allows two with wood spacers or backup cleats for the finish (section 2308.9.2, checked October 2026). That is one state's code. The 2012 IRC wood-wall chapter we read does not state a corner count, so this calculator asks you for the number from your plans and only shows a note if you use fewer than three.
• Top plate. The 2012 IRC, as published by Seattle, caps wood stud walls with a double top plate, lapped at corners and intersections, with end joints offset at least 24 in (R602.3.2). A single plate is allowed with the steel ties of its exception, and on interior nonbearing walls (R602.5). Studs bear on a bottom plate at least 2 in nominal thick and as wide as the studs (R602.3.4).
• Headers. The IRC points to its header tables and figures for the size of a header (R602.7). In the 2012 text, nonbearing walls can use a single flat 2x4 header for openings up to 8 ft when the distance to the nailing surface above is 24 in or less, and then no cripples or blocking are required above the header (R602.7.3). The calculator counts cripples anyway, so subtract them if your plans leave them out.
• Other editions. We could not open the 2021 and 2024 editions of the IRC from the publisher. Your state or city adopts one edition with its own changes, so confirm each point with your building department.

Frequently asked questions

Covering the wall? The drywall calculator counts sheets and screws, and the board foot calculator turns a list of boards into board feet.