Quick-pick estimate based on simplified IRC R602.7 ranges. NOT engineered. Verify with a structural engineer, code-stamped tables, or local inspector before framing.
About this calculator
This header size calculator gives a quick IRC-style recommendation for the built-up header that spans a door or window opening in a wood-framed wall. Choose the wall location (non-bearing, exterior bearing, or interior bearing), the number of floors stacking on top of the wall, and the opening width — the calculator returns a built-up header size (e.g., "two 2x10s" or "three 2x12s") consistent with the simplified tables in IRC R602.7. Non-bearing partition walls take a minimum 2-2x4 header up to 8 ft. Bearing walls add depth as opening width and load increase: roof-only walls go up to 2-2x12 at 10 ft, while two-story bearing walls jump faster. ESTIMATE ONLY — IRC tables are based on specific assumptions (snow load, building width, lumber grade); your inspector or engineer is the final word.
For a non-bearing wall: a (2) 2x6 header is plenty. For an exterior bearing wall carrying roof and ceiling only: (2) 2x8. With one floor above plus the roof: (2) 2x10. With two floors above: (3) 2x10. These come from a simplified read of IRC R602.7 and assume average residential loading — your inspector or engineer is still the final word, especially in snow regions or with wider building widths.
How many jack studs per side for a header?
Up to 4 ft opening: 1 jack each side. 4–8 ft: 2 jacks each side. Over 8 ft: 3 jacks each side, or use engineered LVL with manufacturer-specified bearing. Always include 1 king stud (full-height) outside each jack. Wider doors (garage doors, sliding glass over 6 ft) often need a structural post or trimmer made of multiple jacks built up — confirm with the framing plan.
When do I need an LVL or engineered header instead of dimensional lumber?
Use an LVL (laminated veneer lumber) when opening width exceeds 12 feet, when point loads land on the header (girder bearing), in two-story bearing walls with wide openings, or whenever the architect or engineer specifies one. LVLs are stronger and stiffer than built-up dimensional lumber, span farther, and avoid the gap problems of crowned 2x stock. Anything outside the simplified table this calculator uses should be sized by an engineer.