Door Header Size Calculator
Result
Door Header Size Calculator Determine the required header size for a door or window opening in a load-bearing wall. — free online calculator.
Formula
- Door Header Size Calculator calculates its result from Opening span (ft), Allowable span from selected code/table (ft), Selected header label. It uses the formula Based on IRC Table R602.7 guidelines.Headers are typically doubled 2× lumber with 1/2-in plywood spacer.LVL beams recommended for spans over 6 ft or heavy loads.. Change any input to recalculate the result instantly.
- The main inputs are Opening span, Allowable span from selected code/table, Selected header label. Enter them in the units and format shown in the calculator.
- Keep measurements and project assumptions consistent before comparing or combining values.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Door Header Size
- Opening span: 4 ft
- Allowable span from selected code/table: 6 ft
- Selected header label: Reference header
Using Opening span (ft) = 4, Allowable span from selected code/table (ft) = 6, Selected header label = Reference header, the calculated result is Opening span: 4 | Allowable reference span: 6 | Result: Within supplied reference span | Header: Reference header.
Sample result: Calculating…
Frequently asked questions
What does the Door Header Size calculate?
Door Header Size Calculator Determine the required header size for a door or window opening in a load-bearing wall. — free online calculator.
Which values should I enter?
Enter Opening span, Allowable span from selected code/table, Selected header label using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Based on IRC Table R602.7 guidelines.Headers are typically doubled 2× lumber with 1/2-in plywood spacer.LVL beams recommended for spans over 6 ft or heavy loads..
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.