Trailer Tongue Weight Calculator
Check tongue weight against the 10 to 15 percent safe range.
Tongue weight counts against your vehicle payload and hitch rating, not just the tow rating. Too little tongue weight causes trailer sway, which is the leading cause of towing accidents.
How this calculator works
tongue weight = (trailer + cargo) × tongue percent ÷ 100
Move cargo forward of the trailer axle to raise tongue weight and rearward to lower it. Small shifts matter — moving a heavy item two feet can change tongue weight by a hundred pounds.
Switch the site to metric — the control is in the footer — and your inputs, your results and the tables below follow. The formula, the constants, the guidance text and the sources stay in US units on purpose: that is how the standards they come from are written, and restating them would detach each figure from the document you are meant to be able to check it against.
Where these numbers come from
- SAE J684 (Trailer Couplings, Hitches and Safety Chains) 2019 — tongue weight as a percentage of loaded trailer weight
Check the edition. Codes are amended every few years, and the one your inspector works from may not be the one named above.
Worked example
With empty trailer weight 3000 lb, cargo on the trailer 4000 lb, target tongue weight 12 , this calculator returns 840 lb.
Tongue weight for common trailer loads
Every row here opens the calculator already filled in. Copy that link and the numbers travel with it.
| Job | Size | Tongue weight |
|---|---|---|
| Small utility trailer | 800 lb × 1200 lb × 12 | 240.0 lb |
| Car hauler, loaded | 2200 lb × 3500 lb × 12 | 684.0 lb |
| Travel trailer | 5000 lb × 1500 lb × 13 | 845.0 lb |
| Boat trailer Boats sit lighter on the tongue |
1200 lb × 3000 lb × 8 | 336.0 lb |
| Equipment trailer | 3000 lb × 7000 lb × 15 | 1,500 lb |
Too little tongue weight is what starts a sway. Moving one heavy item two feet forward can add a hundred pounds.
Frequently asked questions
What is the correct tongue weight?
Ten to 15% of the loaded trailer weight for a bumper-pull trailer, and 15 to 25% for a gooseneck or fifth wheel. Below 10% the trailer will sway at highway speed.
What causes trailer sway?
Almost always too little tongue weight, from loading cargo behind the axle. The trailer starts to steer the truck instead of following it. Moving weight forward is the fix, not driving slower.
How do I measure tongue weight?
A tongue weight scale is the simplest tool. Alternatively, take the loaded rig to a public scale and weigh the truck alone, then with the trailer coupled — the difference on the rear axle is close enough.
Does tongue weight reduce what I can carry in the truck?
Yes, directly. Tongue weight sits on the hitch and counts fully against vehicle payload. A 7,000 lb trailer at 12% puts 840 lb into the truck before any passengers get in.