Weight Distribution Calculator
Check axle weights against federal limits before you hit the scale.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Getting caught overweight at a scale is expensive. Federal fines start at hundreds of dollars per axle and can reach thousands for severe violations, plus the cost of offloading or returning to the shipper. This calculator lets you verify your axle weights before you reach the weigh station.
- Enter steer axle weight. Federal limit is 12,000 lbs. Most tractors have a steer axle around 10,000-11,500 lbs when properly loaded.
- Enter drive tandem weight. The federal limit for a tandem drive axle group is 34,000 lbs. This is the most commonly violated limit.
- Enter trailer tandem weight. Also limited to 34,000 lbs federally. The trailer axle weight depends heavily on where the load is positioned in the trailer.
- Check your result. Legal means you are within all federal limits. If overweight, the breakdown shows exactly which axle is over and by how much.
Note: state bridge laws may impose stricter limits. Always check state-specific regulations for your route.
About the Weight Distribution Calculator
Federal law limits gross vehicle weight to 80,000 lbs on the Interstate Highway System. Individual axle limits are: steer axle 12,000 lbs, drive tandem 34,000 lbs, and trailer tandem 34,000 lbs, for a legal maximum of 80,000 lbs. Weight can be transferred between axles by sliding the fifth wheel or trailer tandems. Moving the fifth wheel forward transfers weight from the drive axles to the steer axle. Sliding the trailer tandems forward reduces trailer axle weight and increases drive axle weight. Understanding this allows drivers to redistribute loads without returning to the shipper.
Frequently Asked Questions
How do I reduce drive axle weight without offloading?
Slide the fifth wheel back toward the drive axles. This transfers weight from the drive tandems to the trailer tandems. The rule of thumb is approximately 500 lbs transferred per notch on the fifth wheel slide. Conversely, sliding the fifth wheel forward transfers weight from drives to steer. Always re-check axle weights after adjusting.
What are the fines for overweight trucks?
Federal fines for overweight violations vary by state but typically range from $100-$150 per pound over the limit for axle violations. A drive axle that is 2,000 lbs over can result in a fine of $200-$300 before court costs. Some states impose significantly higher penalties. The carrier, driver, and shipper can all be held liable.
Do state limits differ from federal limits?
Yes. States can and do impose stricter limits than federal law, particularly for bridge weight laws. Some states allow higher weights under permit for special commodities. States also vary in how they apply the bridge formula, which limits weight based on axle spacing. Always verify state-specific limits for your planned route, especially if crossing multiple states.
What is the bridge formula and how does it affect weight limits?
The bridge formula (Formula B) limits the total weight on any group of two or more consecutive axles based on the distance between the outer axles of that group. It prevents bridge damage from concentrated weight. In practice, it most often affects tandems spaced close together. The FHWA provides a bridge formula table and calculator on their website for detailed compliance checking.