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Fifth Wheel Weight Calculator
The primary purpose of this calculator is to answer the question: "How heavy a fifth wheel can I tow with my truck?"
This calculator is designed for fifth wheel trailers, towed by a fifth wheel hitch mounted in the bed of a truck above the rear axle.
In the form below, enter as many pieces of inforamtion as you have, and click the Calculate button at the bottom. The more information you provide, the more accurate the calculation will be. The reverse is also true—the less information you provide, the less accurate the results.
If you are unfamiliar with the weights or abbreviations, you may want to start with Understanding RV Weights.
For additional details, please see the scenarios below the calculator.
* The results of this calculator are approximate. Results may be slightly inaccurate due to conversion and rounding. Weight of liquids vary slightly with temperature, altitude, chemical composition, etc.
Scenario: Maximum trailer weight reduced by GVW
In this scenario you know quite a bit about the truck. You have entered the maximum trailer weight rating, as well as the actual truck weight (GVW) and rear axle weight (RGAW). Since buying the truck, you have installed a heavy toolbox in the bed, increasing the truck weight by almost a 1,000 lbs. Because of this, the calculator found the GVW to be the most restrictive number, and reduced the maximum trailer weight accordingly.
Example, using the 2005 Dodge RAM 1500, regular cab, 4x4, 5.7L HEMI Magnum V8 engine:
As you can see, the calculated result of 2,020 lbs is significantly lower than the maximum specified by Dodge at 8,900 lbs. The large difference is because the manufacturer ratings use the truck weight with standard equipment and driver only. Options and cargo add to the truck weight, reducing towing capacity.
Additionally, the Dodge numbers assume a 15% king pin weight, while the calculator assumes a more restrictive 25%. Enter 15% in the Fifth wheel trailer king pin weight percentage override box and re-calculate, resulting in a higher Maximum Trailer Weight of 3,367 lbs. While the lower percentage makes it look as if you can tow more, you need to find out the actual king pin weight and percentage before settling on this number.
To see how each value affects the calculated maximum trailer weight, try this: Enter the first two values above and click Calculate. Then, enter all additional values, clicking Calculate after each one.
Scenario: Only know the truck's GVWR and GCWR
Example, using the 2002 Ford F-350 truck:
While this result gives you a very rough estimate of the tow vehicles potential, it has the following problems:
Scenario: Only know the hitch maximum king pin weight rating
If you only know the hitch rating as specified by the manufacturer, enter it in the Tow vehicle maximum king pin weight rating box.
Example, using the 2005 Chevrolet Colorado, crew cab, 2WD, Vortec 2800 I-4 engine:
If the maximum king pin weight used in this calculation is from the hitch manufacturer, this result may be highly inaccurate because the hitch rating may have no relevance whatsoever to the truck ratings. On the other hand, if the maximum king pin weight is from the truck manufacturer for this specific vehicle, then the calculation would be more accurate. In either case, using this number alone is insufficient because of the following:
The actual maximum trailer weight rating for this vehicle is 1,700/2,900 lbs (manual/auto transmission), as specified by Chevrolet.
These scenarios illustrate that relying on too little information may cause you to exceed manufacturer ratings. On the other hand, providing the calculator with all relevant weight numbers will produce accurate results.