Header Size Calculator — IRC R602.7 Header Tables
Look up code-compliant header size for any rough opening per IRC R602.7. Covers 2×6 through 2×12 doubled and tripled headers for door and window openings.
Enter Dimensions
Recommended: 10% for standard framing
Results
Studs Needed
15studs
Plate Pieces
2pieces
1 top plate + 1 bottom plate
Total Lineal Feet
167lin ft
Total lumber length to purchase
Wall Area
144sq ft
Editorial Standards
Each calculator is reviewed for formula accuracy, unit consistency, and alignment with current U.S. building practices before publication. We verify outputs against published engineering references and real-world project data. Learn more about our methodology.
A header is the structural beam over a window, door, or other wall opening — it transfers the load that would otherwise pass through the missing studs over to the king studs on either side of the opening. Sizing it correctly is non-negotiable: an undersized header sags, cracks drywall, and fails inspection.
This calculator references IRC R602.7(1) — the residential prescriptive header table — for standard solid lumber headers. For unusual conditions (large openings, heavy loads, tall walls), an engineered LVL or steel beam may be required.
How to Size a Header
IRC R602.7(1) Header Size Quick Reference
(Douglas Fir #2, 2-ply, supporting roof + ceiling only, light snow load)
- 3 ft opening: 2-2x6
- 4 ft opening: 2-2x6 or 2-2x8
- 5 ft opening: 2-2x8
- 6 ft opening: 2-2x10
- 8 ft opening: 2-2x12
- 10 ft opening: 3-2x12 or 1-3/4″ × 11-7/8″ LVL
- 12 ft opening: 1-3/4″ × 14″ LVL (engineered)
For two-story walls, heavy snow loads, or where the header supports a beam from above, step up at least one size. Always verify against the current IRC edition and local amendments.
Frequently Asked Questions
What size header for a 6 ft opening?
For a load-bearing wall supporting roof + ceiling only: 2-2x10 header per IRC Table R602.7(1) (lumber #2 Douglas Fir, light snow loads). For 2-story or heavier loads, step up to 2-2x12 or engineered LVL.
Is a 2x4 header strong enough for a window?
Only for narrow non-load-bearing openings under 3 ft wide. Most residential window and door openings require 2-2x6 (small openings) up to 2-2x12 (large openings). Use the IRC tables, not eyeballing.
Do interior partition walls need real headers?
Non-load-bearing interior partitions can use a single flat 2x4 over openings (per IRC R602.7.5). Anything wider than 8 ft, however, benefits from a 2-2x4 doubled flat header for sag resistance.
What is an LVL header?
Laminated Veneer Lumber (LVL) is engineered wood made of thin wood layers glued together. LVL headers are stronger and stiffer than solid lumber, allowing longer spans with smaller depth. Common sizes: 1-3/4″ × 7-1/4″ to 1-3/4″ × 14″.
How is header depth determined?
Depth × number of plies × lumber grade vs span = code-compliant choice. The deeper the header, the longer the span it can carry. IRC R602.7(1) is the prescriptive table; engineered designs use beam tables from APA or NDS.
Looking for the general calculator?
Calculate how many studs you need for any framing job. Enter wall dimensions and spacing for an instant piece count — supports 2×4 and 2×6 at 16 or 24-inch OC.
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