header span table

Header Span Table

Header span depends on the opening, supported stories, roof and floor loads, snow, species, grade, bearing, and local code.

Inputs

Results

Immediate estimate

Planning max opening8 ftSelected opening is within this limited lookup.

Opening width6 ft

Header2 2x10

Load conditionroof only

ResultWithin lookup

Review the limitations before using this result for planning.

This MVP lookup is limited to selected species, sizes, spacings, and simple loading assumptions. Do not extrapolate.

Headers depend on span, stories, roof/ceiling/floor loads, snow, tributary width, species, grade, bearing, king/jack studs, point loads, and local code.

Diagram

Header opening

Opening width is compared with a limited built-up wood header lookup.

Opening
Header
Supported load

How this calculator works

Choose a simplified load condition, built-up header size, and opening width to compare against a limited planning lookup.

Lookup only

The MVP uses a small conservative planning lookup for common built-up dimensional-lumber headers.

No extrapolation

Unsupported or heavier cases return no recommendation-like result instead of guessing.

Engineering caution

Final header sizing must account for real tributary loads, point loads, bearing, jack studs, and code requirements.

Lookupmatch simplified load condition and built-up header size

Comparisonopening width <= planning max opening

Assumptions

Scope: Small set of conservative built-up dimensional-lumber planning rows.
Not checked: Point loads, girder trusses, garage portals, engineered wood headers, bearing length, and lateral requirements.

Worked examples

Roof-only window header

Simple roof-only opening lookup.

8 ftPlanning max opening

Loaded wall opening

Shows an exceeds-lookup result for a heavier condition.

6 ftPlanning max opening

FAQ

Can I use this for a load-bearing wall?

Only as early screening. Load-bearing openings need verification from adopted tables, plans, or a qualified designer.

Does this cover garage door headers?

No. Garage openings and braced-wall/portal-frame conditions are outside this MVP.

Does it cover LVL headers?

No. Use the LVL beam span calculator with the exact manufacturer table for engineered headers.

Sources and review

2021 International Residential Code, International Code Council, 2021. Accessed 2026-07-16.
Online Span Calculator Help, American Wood Council. Accessed 2026-07-20.
Design Values / Span Tables, American Wood Council. Accessed 2026-07-20.

Reviewed 2026-07-20. Planning estimates only; confirm project-specific requirements.