About the Trailer Tongue Weight Calculator
This trailer tongue weight calculator divides the downward force on your hitch ball (the tongue weight) by the loaded weight of the trailer, then checks the result against the widely used guideline: about 10% to 15% of gross trailer weight for a conventional bumper-pull trailer, and a pin weight of about 15% to 25% of trailer weight for a fifth-wheel or gooseneck. It also shows how many pounds you are below or above that range and how much of your hitch’s tongue-weight rating you are using.
Use it after loading a travel trailer, boat, car hauler or utility trailer and weighing it on a CAT scale or with a tongue weight scale. Too little tongue weight is the classic cause of trailer sway; too much overloads the rear axle of the tow vehicle, lifts the front wheels and reduces steering and braking grip.
Enter the loaded (gross) trailer weight including everything on board, not the empty dry weight from the brochure. The calculator works in any unit — pounds or kilograms — as long as both weights use the same one. Always follow the tow vehicle and hitch manufacturer’s limits, which take priority over a general rule of thumb.
With the default inputs, the tongue weight percentage is 11%. Change any value above to recalculate instantly.
How to use the trailer tongue weight calculator
- 1Load the trailer exactly as you will tow it.
- 2Weigh the tongue with a tongue weight scale, or weigh the trailer and the vehicle with and without it on a truck scale.
- 3Choose the trailer type and enter the tongue weight and the loaded trailer weight.
- 4Enter the lowest tongue-weight rating of your hitch, ball mount and vehicle.
- 5Move cargo forward or back until the percentage sits inside the recommended band.
Formula and method
Tongue weight percentage is the measured tongue weight divided by the gross trailer weight — the full loaded weight of the trailer, including the part resting on the hitch. The recommended band is then simply the trailer weight multiplied by the lower and upper percentages for the trailer type.
If the measured weight is below the minimum, the shortfall is how much extra weight needs to move onto the tongue; above the maximum, it is how much needs to come off. The hitch-use figure compares tongue weight with the lowest tongue-weight rating among your vehicle, receiver, ball mount and ball.
- TW
- Measured tongue (or king-pin) weight
- GTW
- Gross (loaded) trailer weight
Worked examples
5,000 lb travel trailer with 550 lb tongue weight
550 ÷ 5,000 = 11%, inside the 10–15% band of 500–750 lb. The tongue uses 550 ÷ 600 ≈ 91.7% of the hitch rating, so there is little room to add more weight up front.
Boat trailer that is too light on the tongue
380 ÷ 4,800 ≈ 7.9%, below the 10% minimum of 480 lb. Moving the boat forward on the bunks, or shifting gear forward, to add about 100 lb of tongue weight brings it into range and reduces sway.
12,000 lb fifth-wheel camper
A 2,400 lb pin weight on a 12,000 lb fifth-wheel is 20%, right in the middle of the 15–25% band (1,800–3,000 lb). It uses 80% of a 3,000 lb rating — also check the truck’s payload, since pin weight counts against it.
Frequently asked questions
What should my trailer tongue weight be?+
For conventional ball-hitch trailers the common guideline is 10% to 15% of the loaded trailer weight; many towing guides suggest aiming near 12%. Fifth-wheel and gooseneck trailers normally carry 15% to 25% on the pin.
What happens if tongue weight is too light?+
With less than about 10% on the tongue, the trailer’s centre of gravity is too far back and it can start to sway at speed. Once started, sway can build quickly and lead to a loss of control, especially in crosswinds, when passed by large trucks or during sudden steering.
What happens if tongue weight is too heavy?+
Excess tongue weight overloads the tow vehicle’s rear axle and hitch, lifts the front end, and reduces steering and braking traction. A weight-distribution hitch can spread the load but does not raise the hitch’s ratings.
How do I measure tongue weight without a scale?+
You can use a bathroom scale with a lever setup for light trailers, or weigh at a truck scale: weigh the vehicle with the trailer attached (axles separately), then without it, and the increase on the vehicle’s axles is the tongue weight.
Does tongue weight count against payload?+
Yes. Tongue or pin weight is carried by the tow vehicle, so it is subtracted from the vehicle’s payload capacity along with passengers and cargo. Fifth-wheel pin weight often uses up most of a pickup’s payload.