PlumbCut
Free calculator

Built-up header calculator.

Give it the rough opening, the header size, and how many plies, then tell it the wall and the bearing. It lays out the built-up header for one opening and hands you the cut list: how long to cut each piece, what stock to cut it from, the plywood spacers, and the king and jack studs. You get the lineal feet and board feet you can carry straight to the yard.

How is it built
The opening
The cut list
Header members
2 @ 39 in 2x10
Each cut from
8 ft stock
Plywood spacers (1/2 in)
1 @ 39 in
King studs
2
Jack studs
2
Total lineal feet
6.50 ft
Total board feet
10.83 bf
The header detail

Two views like a cut sheet. The plan section looks down through the wall so you can see the members standing on edge and packed flush; the elevation is the straight-on opening with the header, cripples, king and jack studs. Screenshot it and take it to the wall.

PLAN SECTION · looking down through the walloutin2x102x101/2" plywall 3.50 inmembers stand on edge; the 9.25 in depth runs top to bottom (shown in the elevation)ELEVATION · straight ondouble top platecripples2-member 2x10 headerdepth 9.25 inkingjackrough openingrough opening 36 inbrg 1.5brg 1.5
Read this first

A takeoff and cut-list helper, not an engineering tool. It counts material for the assembly you pick and lays it out. It does not tell you what size header to use or which assembly your wall needs. Size, ply count, bearing, and whether an insulated or engineered header is called for all come off the stamped plans, the building department, or the engineer. When in doubt, size up and ask.

Read the guide
How to size a header for a window or door

A framer's rules of thumb for sizing headers over openings: span-to-size, ply and width, king and jack studs, and when to call the engineer.

How the numbers come out

The same layout you’d do on the tailgate.

Piece length

Each header piece is the rough opening plus a bearing at each end. A 36 in opening with 1.5 in of bearing per end makes a 39 in piece. You cut one of those for every ply in the stack.

Spacers

Two plies of 2x stack to 3 in, but a 2x4 wall is 3.5 in deep. Half inch plywood strips pack the stack out flush. We count the strips and cut them to the same length as the header.

Kings and jacks

Two king studs run full height, one at each end. The jacks sit just inside them and carry the header. One jack per side is standard, and wider spans often call for two.

Lineal and board feet

Total lineal feet is the piece length times the ply count. Board feet run the lineal footage times the board-foot rate for the size, so a deeper header eats more material for the same span.

While you’re here

This is the free warm-up. PlumbCut reads your whole plan set and prices the entire frame: every wall, all the headers, the sheathing, and the trusses. Laying out one header is the easy part. Let the AI do the takeoff on your next real job and hand you a customer-ready bid.