# 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.

---

Source: https://vastcalc.com/calculators/construction/header-size
Category: Construction
Last updated: 2026-04-21