Carga máx viga madeira
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The maximum load calculator for wooden beams determines the highest uniform load a simply supported wooden beam can withstand using the formula q = 8·fm·W/L². This tool is useful for structural projects like wooden floors or bridges, ensuring safety and efficiency. The calculation relies on the wood's flexural strength (fm), the section modulus (W) of the beam, and the square of the beam's length (L²). Accurate inputs are critical to prevent overloading.
The formula assumes a uniformly distributed load with rigid supports at both ends. The section modulus (W) depends on the beam's cross-sectional dimensions, while flexural strength (fm) varies by wood type and treatment. This calculator is ideal for planning light structures or checking existing beams. However, for real projects, consult an engineer to confirm results. The calculation represents ideal conditions, so real-world factors like moisture, wood defects, or eccentric loads are not included.
Use this tool carefully: the formula assumes rigid supports and uniform loading, which may not match real scenarios. Theoretical load values require safety factors as per technical standards (e.g., ABNT NBR 7190). Always use consistent units (e.g., meters for L and MPa for fm) and validate results with engineering expertise for critical applications.
Frequently asked questions
What formula does the calculator use?
It uses q = 8·fm·W/L², where q is maximum load, fm is wood's flexural strength, W is section modulus, and L is beam length.
Which units should I use?
Use meters for length (L), MPa for flexural strength (fm), and cm³/m³ for section modulus (W), depending on beam dimensions.
Does the calculator consider self-weight?
No, the formula assumes external uniform load. Calculate self-weight separately and add it to the external load.
Can I use it for different wood types?
Yes, as long as you have the specific fm value for the wood type (e.g., sawn, laminated, or treated wood). Check technical standards for accurate values.
Why does beam length affect maximum load?
Length is squared in the denominator (L²), making longer beams significantly weaker. Increasing length reduces load capacity in a non-linear way.