Use the loaded weight of the trailer (with water, gear and propane), not its dry weight from the brochure, which can be 1,000 lb or more lighter.
How the towing calculator works
TowCapacityCalc multiplies the loaded trailer weight by the tongue percentage to get the tongue (or fifth-wheel pin) weight, then compares it with the usual range for the trailer type: 10–15% for a conventional bumper-pull trailer, 15–25% for a fifth wheel and 20–25% for a gooseneck. It divides the trailer weight by your towing capacity and flags anything above the 80% rule of thumb, subtracts people, cargo and tongue weight from payload, and suggests the lowest receiver hitch class rated for both the trailer and the tongue weight. Weights work in pounds or kilograms.
Receiver hitch class chart
| Class | Max trailer | Max tongue | Typical use |
|---|---|---|---|
| Class I | 2,000 lb | 200 lb | cars and small crossovers, bike racks, small utility trailers |
| Class II | 3,500 lb | 350 lb | crossovers and minivans, small boats and campers |
| Class III | 8,000 lb | 800 lb | pickups and SUVs, most travel trailers and boats |
| Class IV | 10,000 lb | 1,000 lb | full-size pickups and SUVs, larger campers |
| Class V | 20,000 lb | 2,000 lb | heavy-duty pickups, equipment and car haulers |
Ratings are typical maxima; your hitch’s label and the vehicle’s manual are the final word. The towing capacity, payload, GVWR, GCWR and axle ratings all apply at once, and the lowest one is your real limit. Weigh the loaded rig at a truck scale before a long trip.
Frequently asked questions
Where do I find my towing capacity?
In the owner’s manual or the maker’s towing guide for your exact cab, engine, axle ratio and tow package. Payload is on the door-jamb sticker.
Should I use dry weight or GVWR of the trailer?
Use the loaded weight, or the trailer’s GVWR to be safe, since that is the most it can weigh when full.
What is GCWR?
Gross combined weight rating: the maximum weight of the loaded vehicle and loaded trailer together.
Is TowCapacityCalc free?
Yes, with no sign-up or ads, and your numbers stay in your browser.
Is this a substitute for my vehicle ratings?
No. It is an estimate. Always follow the owner’s manual, the door-jamb sticker and the hitch and trailer ratings, and weigh your rig at a scale.