Boat Trailer Tongue Weight Calculator

Tongue weight is the part of a loaded trailer’s weight that rests on the hitch ball. Boat trailer makers recommend 5 to 10 percent (Karavan), 7 to 10 percent (Magic Tilt) or 7 to 12 percent (EZ Loader) of the total weight of the trailer, boat, motor, fuel and gear. For a 3,000-pound rig, 7 to 10 percent is 210 to 300 pounds on the tongue. The calculator above gives the target for any range and shows what share a measured tongue weight is; use the range in your own trailer’s manual.

What Percent of the Trailer Weight Should Be on the Tongue?

Trailer maker’s manual	Tongue weight	Notes
Karavan Trailers, marine owner’s manual	5 to 10% of the loaded trailer’s total weight	Holds up to loads of about 4,000 lb; above that, balance enough tongue weight against stress on the tow vehicle and hitch
Magic Tilt, trailer safety manual	7 to 10% of the loaded trailer’s total weight	Holds until boats of about 9,000 lb and heavier
EZ Loader, 2024 owner’s manual	7 to 12% of the trailer’s gross vehicle weight	Never more than the hitch’s maximum rating
McClain Trailers, boat trailer owner’s manual	6 to 10% for small trailers, 10 to 15% for large trailers	A rule of thumb; ask the maker about your trailer

Every one of these percentages is of the whole loaded trailer: the boat, motor, fuel and gear plus the trailer itself, not the boat alone. Karavan gives the example of a 2,000-pound loaded trailer, which should have 100 to 200 pounds on the tongue; Magic Tilt’s 7 to 10 percent makes that 140 to 200 pounds. The calculator starts at 7 to 10 percent because it lies inside all four ranges (McClain’s for small trailers). If your trailer’s manual gives a different range, enter it.

How to Measure Tongue Weight

Load the trailer the way you tow it, with the boat, motor, fuel and gear aboard. Karavan and Magic Tilt say to check the weight with the tongue parallel to the ground, and they and EZ Loader (for lighter boats) all mention a bathroom scale. For a heavier rig, McClain describes a certified truck scale:

Enter the total and the tongue weight above for the percentage. While at the scale, McClain suggests also checking that the tow vehicle stays within its gross vehicle weight rating and the whole combination within its gross combined weight rating.

Too Little or Too Much Tongue Weight

• Too little. The trailer can sway from side to side (fishtail), which the trailer makers warn can cause a loss of control. Move gear such as a gas tank, the anchor or tackle forward in the boat; if that isn’t enough, some trailers let you move the axle back, as the Karavan and Magic Tilt manuals describe.
• Too much. Karavan warns of undue stress on the tow vehicle, the hitch and the coupler, and McClain that the tow vehicle’s front wheels can carry too little weight, hurting steering and traction. Move gear back in the boat, or move the axle forward where your trailer allows it.

Stay Within Your Hitch and Tow Vehicle Ratings

A percentage never overrides a rating. EZ Loader’s manual says the weight on the coupler must never be more than the hitch’s maximum rating, even where the percentage would allow more, and that the trailer’s gross vehicle weight rating must not exceed the capacity of your hitch. Check the tongue weight and towing ratings in your tow vehicle’s owner’s manual too, as Magic Tilt advises.

Worked Example

A boat, motor, fuel, gear and trailer weighing 3,000 pounds together should put 210 to 300 pounds on the tongue at 7 to 10 percent, or 150 to 300 pounds at Karavan’s 5 to 10 percent. If the scale shows 270 pounds, that is 9 percent, inside both ranges, and the trailer’s axles carry the other 2,730 pounds. For a large trailer, McClain’s own example is 6,000 pounds at 10 to 15 percent: 600 to 900 pounds.

To add up the loaded trailer weight, use the Boat Weight Calculator; fuel adds weight quickly, and the Fuel and Water Weight Calculator converts gallons to pounds. On the water, the boat’s capacity plate limits the load instead: see the Boat Capacity Calculator.

Frequently Asked Questions