# Header Size Calculator

Determine the right header size for door and window openings. Based on span width, wall type (bearing vs non-bearing), and stories supported.

## What this calculates

Headers carry the load above door and window openings, so using the right size is critical for structural safety. This calculator recommends a header size based on your opening width, whether the wall is load-bearing, and how many stories are above it. Always verify with your local building code or a structural engineer for critical applications.

## Inputs

- **Opening Span** (ft) — min 0, max 20 — Standard door: 3 ft, garage: 8-16 ft
- **Wall Type** — options: Load-Bearing Wall, Non-Bearing Wall — Bearing walls carry roof/floor loads above
- **Stories Supported** — options: 1 Story (roof only), 2 Stories (floor + roof) — Number of floors above the header
- **Header Construction** — options: Double (2x lumber + plywood), LVL (Laminated Veneer Lumber), Single (non-bearing only)

## Outputs

- **Span Width** (in)
- **Recommended Header** — formatted as text
- **Header Depth** (in)
- **Jack Studs Per Side** (studs)
- **Approximate Load Capacity** — formatted as text — Rough estimate -- consult an engineer for critical loads

## Details

## Header Sizing Rules of Thumb

For standard residential construction with double 2x headers in load-bearing walls supporting one story:

| Opening Span | Header Size | Header Depth |
|-------------|------------|-------------|
| Up to 4 ft | Double 2x6 | 5.5" |
| 4 to 6 ft | Double 2x8 | 7.25" |
| 6 to 8 ft | Double 2x10 | 9.25" |
| 8 to 10 ft | Double 2x12 | 11.25" |
| Over 10 ft | LVL or steel | Varies |

These are general guidelines based on the IRC (International Residential Code) prescriptive tables for standard residential loading conditions. Your local code may have different requirements.

## Load-Bearing vs. Non-Bearing

**Load-bearing walls** carry weight from the roof, floors, or walls above. They need properly sized headers to transfer that load to the jack studs and down to the foundation.

**Non-bearing walls** (partition walls) only support the weight of the wall itself. Headers in these walls can be much smaller -- often a double 2x4 is sufficient for spans up to 6 feet.

## Header Construction Methods

**Double 2x lumber:** Two pieces of dimensional lumber with a 1/2" plywood spacer to match 2x4 wall thickness (3.5"). This is the most common residential method.

**LVL (Laminated Veneer Lumber):** Engineered beams that can span greater distances with less depth. More expensive but necessary for wide openings like sliding glass doors.

**Steel:** Required for very wide openings (16+ feet) or heavy loads. Must be specified by a structural engineer.

## Jack Stud Requirements

Jack studs (also called trimmer studs) sit under each end of the header and transfer the load down. Wider openings need more jack studs:

- **Spans under 4 ft:** 1 jack stud per side
- **Spans 4-8 ft:** 2 jack studs per side
- **Spans over 8 ft:** 3 jack studs per side

## Frequently Asked Questions

**Q: What size header do I need for a 6-foot opening?**

A: For a 6-foot opening in a load-bearing wall supporting one story, use a double 2x8 header. If supporting two stories, step up to a double 2x10. In a non-bearing wall, a double 2x4 or double 2x6 is typically sufficient.

**Q: Do non-bearing walls need headers?**

A: Technically yes, but the header can be minimal. A double 2x4 or even a flat 2x4 is usually adequate for non-bearing walls with standard door openings. The header just spans the opening to support the short cripple studs above.

**Q: When should I use an LVL header instead of dimensional lumber?**

A: Use LVL headers for spans over 10 feet, when you need a shallower header depth (to fit above tall doors or windows), or when carrying heavy loads. LVL is stronger pound-for-pound than dimensional lumber and does not warp or shrink.

**Q: How do I know if a wall is load-bearing?**

A: Load-bearing walls typically run perpendicular to floor joists and sit directly above the foundation or a beam below. Exterior walls are almost always load-bearing. Interior walls parallel to the joists are usually non-bearing, but there are exceptions. When in doubt, consult a structural engineer before removing any wall.

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Source: https://vastcalc.com/calculators/construction/header-size
Category: Construction
Last updated: 2026-04-08