Window & Door Header Calculator
Headers carry the load from above a window or door opening to the king studs on each side. Size depends on opening width, number of floors above, and whether it's an exterior (load-bearing) or interior wall.
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How to Use This Calculator
- 1Enter your measurements in the fields above. Use the units shown next to each field (ft, in, etc.).
- 2Click Calculate to get your material estimate instantly.
- 3Review the highlighted result — it shows the key quantity you need to order.
- 4Use Copy Results to save your estimate, or bookmark the URL — your inputs are encoded in the link.
Pro tip: Always add 10% to your material order to account for waste, cuts, and defects.
Frequently Asked Questions
What size header do I need for a 6-foot opening?
For a 6-foot exterior opening on the top floor (roof load only), use doubled 2×10 headers. With one floor above, use doubled 2×12. Always check your local building code — some jurisdictions require engineered headers for openings over 4 feet.
Do interior non-load-bearing walls need headers?
Technically, non-load-bearing walls don't require engineered headers — a doubled flat 2×4 works for most interior door openings. However, many codes require at least a single 2×4 header for any opening in a partition wall for rigidity.