What size header do I need for a 3-foot door?

A doubled 2x6 is sufficient for a 3-foot interior or exterior door in most single-story applications. For two-story homes where the header carries a floor and roof load, step up to a doubled 2x8 or 2x10. Always consult your local building code or an engineer for multi-story or high-load situations.

How long should the header be?

The header must be at least as wide as the rough opening plus 3 inches to bear on the jack studs (1.5 inches on each side). Most builders add an extra few inches for bearing. This calculator adds 12 inches total to the opening width to ensure proper bearing on both sides.

What is the difference between a header and a lintel?

In wood-frame construction, header and lintel are often used interchangeably. Technically, a lintel is a masonry term for the beam over a masonry opening, while a header refers to the wood beam in stick framing. In practice, most US builders call it a header regardless of the material.

Do non-load-bearing walls need headers?

Non-load-bearing (partition) walls do not need structural headers. A single flat 2x4 across the top of the opening is sufficient to support the short cripple studs above. However, many builders install a full header anyway for simplicity and in case the wall is later designated as load-bearing.

Can I use LVL instead of doubled lumber for headers?

Yes. Laminated veneer lumber (LVL) beams are stronger than dimensional lumber of the same depth and are ideal for wide openings. A single 3.5-inch-wide LVL can replace a doubled 2x header and fills the wall cavity perfectly. LVL headers are available in depths from 5.5 to 18 inches.

How many king studs and jack studs do I need per opening?

Each opening requires two king studs (one on each side, running full height from bottom plate to top plate) and two jack studs (trimmers, cut to the height of the bottom of the header). For openings wider than 6 feet, some codes require doubled jack studs on each side for additional bearing support.

Header Calculator

Header calculator: What size header for my opening? Free tool for door & window spans — covers common header sizes.

Ad — 728x90 — Leaderboard

Enter Your Measurements

How to Use This Calculator

1Enter the rough opening width in feet.
2Enter the total number of openings.
3Click Calculate — get header lumber length, king studs, and jack studs.

Ad — 728x90 — Mid-Page

About This Material

Headers are horizontal structural beams that span door and window openings, transferring the roof, floor, and wall loads above the opening around it to the jack studs (trimmers) and king studs on each side. Header size is determined by the span width and the load being carried — a 3-foot door in a single-story wall may only need a doubled 2x6, while a 6-foot sliding door or 8-foot garage header may require a 4x12 or engineered LVL beam. Standard headers are built from two pieces of dimensional lumber with a 1/2-inch plywood or OSB spacer sandwiched between them to match the 3.5-inch or 5.5-inch wall thickness. Pre-made engineered LVL headers are available in standard lengths and eliminate the need for site-built assemblies. In non-load-bearing walls, a single flat 2x4 can serve as a header. Header lumber costs vary widely from $10 for a small doubled 2x6 header to $80 or more for a large LVL beam.

Next Steps:

Stud Calculator →Exterior Sheathing Calculator →

Installation Tips

•Build headers from doubled 2x lumber with a 1/2" plywood spacer to match wall width.
•Or use LVL (laminated veneer lumber) for larger spans.
•Install with crown up.

Common Mistakes to Avoid

Undersizing headers for the span and load.
Not adding jack studs (trimmers) to support the header ends.
Forgetting the cripple studs above the header.

Header Calculator

How to Use This Calculator

About This Material

Installation Tips

Common Mistakes to Avoid

Frequently Asked Questions

Related Calculators

Stud Calculator

Bottom Plate Calculator

Top Plate Calculator

Exterior Sheathing Calculator