Tongue weight calculator

How much tongue weight should a trailer have?

Ford’s RV & Trailer Towing Guide (2015) says tongue load should be 10–15% of the total loaded trailer weight, and king pin load on a fifth-wheel trailer 15–25%. Your vehicle’s and hitch’s own limits come first.

Example

A conventional trailer that weighs 5,000 lb loaded should put 500 to 750 lb on the hitch. A 12,000-lb fifth-wheel trailer should put 1,800 to 3,000 lb on the king pin.

Why does tongue weight matter?

NHTSA notes that too little tongue weight can cause the trailer to sway, and too much tongue weight can cause many problems. Manufacturers consider the loaded trailer’s weight when they specify tongue weight.

How do I change the tongue weight?

By moving cargo: load placed ahead of the trailer axle adds tongue weight, and load behind the axle takes it away.

Should I weigh it?

Yes — estimates are no substitute for a scale. Weigh the loaded trailer and the tongue, then enter the measured tongue weight to see the percentage.

Does the tongue weight count against my truck's payload?

Yes. The tongue weight is carried by the tow vehicle, so it is part of the load the vehicle's rear axle carries, along with passengers and cargo. If a truck's payload rating is 1,500 lb and 400 lb of people and 100 lb of gear are on board, 1,000 lb remains for the tongue. A 7,500 lb trailer at 10% to 15% needs 750 to 1,125 lb, so the upper end would not fit. Take the actual payload figure from the label on your vehicle's door jamb.

What if my measured tongue weight falls outside the range?

Move cargo and measure again. A 7,500 lb trailer with a measured tongue weight of 450 lb is only 6.0% of the trailer, which the calculator flags as low; one with 1,300 lb is 17.3%, flagged as high. Shifting heavy items forward of the trailer axle raises the figure, and moving them back lowers it.

How the figures are worked out

The calculator multiplies the loaded trailer weight by the recommended share. For a conventional trailer that hitches to a ball on a bumper or receiver, the share is 10% to 15%. For a fifth-wheel or gooseneck trailer, whose weight rests on the king pin over the truck bed, the share is 15% to 25%. The shares come from Ford's RV & Trailer Towing Guide. The weight used is the loaded trailer weight, including water, propane, tools and gear, not the empty weight on the sales brochure. If you enter a measured weight, the tool shows what percentage of the trailer it is and whether it falls within the range.

Worked example: a 7,500 lb trailer and a 15,000 lb fifth wheel

For a conventional trailer that weighs 7,500 lb loaded, the range is 10% × 7,500 = 750 lb to 15% × 7,500 = 1,125 lb. For a fifth wheel of 15,000 lb the king pin range is 2,250 to 3,750 lb (15% to 25%). These figures must then be compared with the limits of the hitch, the receiver and the vehicle, all of which can be lower than the calculated range.

Why too little or too much is a problem

With too little weight on the hitch, the trailer can sway from side to side, and the swing can build up. Too much weight on the ball pushes the rear of the tow vehicle down, lifts the front and reduces steering and braking, and may overload the rear axle or tires. NHTSA's trailer guidance says both conditions are a problem. A weight distribution hitch moves part of the tongue weight to the front axle and the trailer axles, but it does not change the tongue weight itself and has its own rating.

Common mistakes

Using the dry or empty weight of the trailer gives a range that is too low; weigh it loaded. Treating the 10% to 15% as a limit instead of a target is another: the hitch and the vehicle each have a maximum tongue weight, and the lowest of these ratings governs. Mixing up the trailer's gross weight with the tongue weight, or counting the tongue weight twice in the gross combination weight, also happens. Finally, estimates are no substitute for a scale: weigh the tongue with the trailer level, as it would be when towing, and recheck after loading changes.

Sources: Ford Motor Company, RV & Trailer Towing Guide (2015), tongue load 10-15% for conventional trailers and king pin load 15-25% for fifth-wheel trailers; National Highway Traffic Safety Administration (NHTSA) trailer towing safety guidance. Check your vehicle owner's manual and the hitch label for the limits that apply to you. Related: stopping distance calculator, gas mileage calculator and fuel cost calculator.