Select a header size from the drop-down menu to determine the maximum span that the header can accommodate.
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Door Header Size Formula
The following table is used by the calculator above to determine the door header size and maximum span.
| Header Size | Maximum Span |
| 4×4 | 4 feet |
| 4×6 | 6 feet |
| 4×8 | 8 feet |
| 4×10 | 10 feet |
| 4×12 | 12 feet |
What is a door header?
A door header is a beam, typically made out of wood, that spans the opening of a doorway, stairway, skylight, or other framing member.
How big should the door header be?
A door header is sized so that is 2 to 4 times as big as the surrounding framing members.
How to calculate door header size?
To calculate a door header size, first, determine the maximum span of the door. In this example, the door is 8 feet across.
Then, reference the table above to determine the correct header size. For this example, that would be a 4×8 header
