Fifth-Wheel Pin Weight Calculator
Estimate the pin (kingpin) weight of a fifth-wheel or gooseneck trailer as a percentage of its loaded weight, and check it against the truck’s payload.
How it works
Pin weight = loaded trailer weight × pin% · Bed load = pin weight + hitch weight · Remaining = payload − bed load
A fifth-wheel or gooseneck carries far more of its weight on the tow vehicle than a bumper-pull does — typically 15–25% versus 10–15% — because the coupling sits over the truck’s rear axle rather than behind the bumper. That pin weight, plus the weight of the in-bed hitch itself, is what actually counts against the truck’s payload rating, so a heavy fifth-wheel can exceed payload long before it reaches the tow rating. Passengers and cargo still have to fit under payload too, so subtract the pin and hitch first to see what is left.
Worked example
A 12,000 lb fifth-wheel at a 20% pin weight puts 2,400 lb on the kingpin. Add a 200 lb hitch and the truck bed carries 2,600 lb; against a 3,000 lb payload rating that leaves 400 lb for passengers and gear.
Frequently asked questions
What percentage is fifth-wheel pin weight?
Usually 15–25% of the loaded trailer weight, with 20% a common planning figure; goosenecks tend toward 20–25%. It is much higher than a bumper-pull’s 10–15% because the pin sits over the truck’s axle, which is also what makes fifth-wheels tow so stably.
Does the hitch weight matter?
Yes. A fifth-wheel or gooseneck hitch adds 100–200+ lb of hardware sitting in the bed, and that load counts against payload just like the pin weight does. Include it when checking whether the truck is within its rating.
Why does pin weight matter more than tow rating?
Because payload usually runs out first. A big pin weight plus passengers and cargo can exceed the door-jamb payload rating while the trailer is still well under the tow rating — the truck is overloaded even though it "can pull it."
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This calculator is for educational purposes. Double-check important results before acting on them.