How the towing capacity calculator works
Your safe towing limit is set by the GCWR (gross combined weight rating) — the most your truck and trailer are allowed to weigh together, fully loaded. Subtract everything riding in the truck (its curb weight plus passengers and cargo) and what is left is how much trailer you can actually pull. Enter the four numbers above and the calculator shows your available capacity and whether your trailer fits inside it.
GCWR, GVWR, and curb weight explained
- GCWR — gross combined weight rating: the truck and trailer combined ceiling.
- GVWR — gross vehicle weight rating: the loaded truck ceiling on its own (used by the payload calculator).
- Curb weight — the truck empty, with fluids and a full tank but no people or cargo.
- Tongue weight — the downward load the trailer coupler puts on the hitch, normally 10 to 15% of the loaded trailer weight.
Why available towing is less than the brochure number
The headline tow rating on a window sticker is measured with an almost empty truck — one 150 lb driver and nothing else. Every passenger, tool box, cooler, and fuel top-off eats into that number. Working from GCWR and your real loaded weight gives the honest figure for the day you actually tow.
Tongue weight and the 10-15% rule
Aim for tongue weight between 10% and 15% of the loaded trailer weight. Too little makes the trailer sway; too much overloads the rear axle and steals payload. The calculator shows the target range for your trailer so you can position the load over the axles to hit it.
Payload vs towing capacity
Towing capacity is about the combined limit; payload is about what rides inside the truck — including the trailer’s tongue weight. A truck can run out of payload long before it runs out of towing capacity, so check both with the Payload Calculator.
Frequently asked questions
Where do I find my GCWR?
It is in the owner’s manual and often on the door-jamb placard or the manufacturer towing guide for your exact configuration.
Does tongue weight count against towing capacity?
Tongue weight counts against the truck’s payload and rear axle rating, not its towing capacity, but it still has to fit within GVWR — another reason to check payload too.
What if I am over capacity?
Lighten the trailer, move cargo out of the truck, or step up to a vehicle with a higher GCWR. Towing over the rating stresses the brakes, drivetrain, and frame.