RV Towing Capacity Calculator

This calculator checks whether a tow vehicle can safely handle a loaded trailer by working through tongue weight, total payload, and how much capacity is left before the vehicle's rated limit. Tongue Weight -- the downward force the trailer exerts on the hitch -- is the product of Trailer Weight and Tongue Weight Percentage, so the two move it by exactly the same proportion: a 10% increase in either one raises Tongue Weight by the same amount. Vehicle GVWR has no effect on Tongue Weight at all, since tongue weight is purely a property of the trailer and how it's loaded, not the tow vehicle. Remaining Capacity, on the other hand, is dominated by Vehicle GVWR by a wide margin over every other input: it's the one term that appears with a full positive share in the vehicle's headroom calculation, while Trailer Weight and Tongue Weight Percentage only reduce it indirectly, through the smaller Tongue Weight figure they jointly determine.

Safety Margin follows the same ranking, though by a narrower margin, because Vehicle GVWR sits on both sides of that percentage -- in the capacity figure being divided and in the rating it's divided by -- which partially cancels its own effect. Passenger Weight and In-Vehicle Cargo Weight both add directly to Total Payload, but neither one touches Gross Combined Weight or Tongue Weight -- those are driven entirely by the trailer side of the equation. This is a simplified model of a real GCWR/payload check -- always confirm against your specific vehicle's manufacturer rating, not just the numbers here.