Select a header size from the drop-down menu to determine the maximum span that the header can accommodate.

Door Header Size Formula

The following table is used by the calculator above to determine the door header size and maximum span.

Header SizeMaximum Span
4×44 feet
4×66 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