Beam Span Calculator
Calculate maximum beam spans based on lumber size, species, and load requirements. Get recommended spans for floor and roof applications.
Beam Specifications
Beam Size:
Species / Grade:
8 ft
4 ft16 ft
Half the distance to beams on each side
PSF
PSF
Presets:
Recommended Maximum Span
4.5 ft
Theoretical max: 5.6 ft (governed by bending)
📊Max (Bending)
5.6 ft
📉Max (Deflection)
8.0 ft
📐Section Modulus
21.39 in³
📏Moment of Inertia
98.93 in⁴
Load Capacity by Span:
8 ft span24 PSF max
10 ft span16 PSF max
12 ft span11 PSF max
14 ft span8 PSF max
16 ft span6 PSF max
Selected Beam:
2x10 (1.5" x 9.25")
SPF #2
Important Notes
Consult Local Codes
Always verify with local building codes and a structural engineer for critical applications.
Safety Factor
Recommended spans include a 20% reduction from theoretical maximums for safety.
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: Standard Mathematical References
by Various
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.