A header is a structural element that spans over a door or window opening to support the load above. It transfers the weight from the wall above the opening to the supporting studs on each side.

Door Header Size Calculator

Q: How do I calculate header size?

Header size depends on opening width, wall type (load-bearing vs non-load-bearing), header material, story height, and roof load. The formula considers load factors, material strength, and safety factors.

Q: What is bearing length?

Bearing length is the distance the header extends beyond the opening on each side. It ensures the header has adequate support and typically ranges from 3-6 inches depending on header size and load requirements.

Q: How do I support a header?

Headers require proper support framing including jack studs (directly under the header), king studs (full-height studs on each side), and cripples (short studs above the header). Follow local building codes for specific requirements.

Q: What are code requirements?

Local building codes specify minimum header sizes, bearing lengths, and support requirements. Always consult your local building department for specific code requirements in your area.

Header Parameters

Opening Width

Width of the door opening

Wall Type

Type of wall construction

Header Type

Material type for header

Story Height

Height of the story above

Roof Load

Expected roof load (default: 20 PSF)

Calculation Results

Door Header Size Calculator: Your Complete Guide to Door Framing

Proper door header sizing is crucial for structural integrity and safety. Our Door Header Size Calculator helps you determine the correct header size for your door openings.

Understanding Door Header Requirements

Proper header design is essential for several reasons:

Structural Support: Transfers loads around openings
Safety: Prevents wall collapse
Compliance: Meets building code requirements
Stability: Maintains wall integrity
Durability: Ensures long-term performance

How to Use the Door Header Calculator

Enter Opening Width: Input door opening width
Select Wall Type: Choose load-bearing or non-load-bearing
Choose Header Type: Select material type
Enter Story Height: Specify height above
Enter Roof Load: Specify expected load

Header Calculation Formulas

Basic Header Formula:
Header Size = (Opening Width × Load Factor) / (Material Strength × Safety Factor)
Where:
Load Factor = Based on wall type and story height
Material Strength = Based on header type
Safety Factor = Typically 1.5

Common Header Types and Properties

Wood Headers:
- 2x6: Up to 4' openings
- 2x8: Up to 6' openings
- 2x10: Up to 8' openings
- 2x12: Up to 10' openings
Steel Headers:
- 3-1/2": Up to 6' openings
- 5-1/4": Up to 8' openings
- 7": Up to 10' openings
- 10": Up to 12' openings
LVL Headers:
- 3-1/2": Up to 8' openings
- 5-1/4": Up to 10' openings
- 7": Up to 12' openings
- 9-1/4": Up to 14' openings

Real-World Examples

Example 1: Standard Interior Door

Opening Width: 36 inches
Wall Type: Non-Load Bearing
Header Type: Wood
Story Height: 8 feet
Roof Load: 20 PSF
Results:
- Required Header: 2x6
- Bearing Length: 3 inches each side
- Safety Factor: 1.5
- Load Capacity: 1,200 lbs

Example 2: Exterior Door

Opening Width: 48 inches
Wall Type: Load Bearing
Header Type: LVL
Story Height: 10 feet
Roof Load: 40 PSF
Results:
- Required Header: 3-1/2" LVL
- Bearing Length: 4 inches each side
- Safety Factor: 1.5
- Load Capacity: 2,400 lbs

Frequently Asked Questions

What is a header?

A structural element that spans over an opening to support the load above.

How do I calculate header size?

Consider opening width, wall type, material, and load requirements. Use our calculator for specific requirements.

What is bearing length?

The distance the header extends beyond the opening on each side.

How do I support a header?

Use proper jack studs, king studs, and cripples according to code requirements.

What are code requirements?

Follow local building codes for minimum header size, bearing length, and support requirements.