Calculator Category
Load & Weight
Calculators
Solutions for load distribution, weight compliance, and cargo optimization. Stay within legal weight limits on all axles to avoid costly DOT fines.
Freight Class Calculator
Estimate your LTL freight class based on shipment density and dimensions.
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Axle Weight Calculator
Check legal limits and estimate weight shifts for sliding trailer tandems or fifth wheels.
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Understanding DOT Weight Limits & Compliance
Maintaining proper weight distribution is essential for commercial vehicle safety, road infrastructure preservation, and absolute legal compliance. Overweight violations are among the most common and financially devastating citations in the trucking industry.
Critical Weight & Freight Factors:
- Strict Axle Weight Limits: Most interstate regulations rigorously limit steering axles to 12,000 lbs and tandem axles to 34,000 lbs. Even if your gross weight is under 80,000 lbs, you can still be cited if the load is improperly distributed across your axles.
- The Federal Bridge Formula: This mathematical formula determines the maximum weight any set of axles on a commercial motor vehicle may safely carry on all interstate highways to prevent bridge collapse.
- Freight Density (PCF): For Less-Than-Truckload (LTL) carriers, cargo density determines your NMFC freight class, which directly impacts your shipping rates, insurance liability, and how many units can be safely stacked inside the trailer.
Always verify your exact distribution after loading by visiting a certified CAT scale. Use our free calculators to estimate your freight class before quoting shipping rates, ensuring you protect your margins.
Frequently Asked Questions
What is the maximum weight for a semi-truck?
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The federal maximum gross vehicle weight for commercial trucks on the Interstate System is 80,000 pounds, unless the vehicle has a special permit for an oversized or overweight load.
What are the federal axle weight limits?
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Under federal regulations, the maximum allowable weight is 20,000 pounds on a single axle and 34,000 pounds on a tandem axle group. Steering axles are typically limited to 12,000 pounds.
What is a freight class?
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Freight class is a standardized classification system used by LTL (Less-Than-Truckload) carriers to determine shipping rates. It is heavily based on cargo density (PCF), stowability, handling, and liability.