Free Window Header Size Calculator
Determine the required header depth for a window or door opening based on the span width and the number of supported floors.
Minimum Header Depth
6 in
Minimum Header Depth vs Opening Span
How to Size a Window or Door Header
General Rules of Thumb
For load-bearing walls, header depth increases with span:
Add 2 inches of depth for each additional floor supported above the opening. Non-bearing walls typically need only a flat 2x4 header for plate support.
Important Note
This calculator provides general guidelines. Always consult local building codes and an engineer for final header sizing, especially for spans over 8 feet or multi-story loads.
Example Calculation
A 4-foot window opening in a load-bearing wall supporting one floor above.
- 01Span = 4 ft, load-bearing wall, 1 floor above
- 02Base header depth for 4 ft span = 6 inches
- 03Additional depth = (1 - 1) x 2 = 0 inches
- 04Header size = 2x6 (doubled) or equivalent LVL
- 05Jack studs needed = 1 per side
Frequently Asked Questions
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