Trailer weight vs safe capacity
Green is within limits; staying under 80% adds a safety margin.
Home / US Calculators / RV Towing Capacity
RV & Towing
RV Towing Capacity Calculator
Find how much trailer you can safely pull from your GCWR, curb weight and cargo, plus a tongue-weight target and a clear within-limits verdict. Weigh your loaded rig to confirm.
Available towing capacity
8,100 lb
Trailer weight—
Capacity used—
Target tongue weight (12%)—
Status—
Available capacity is limited by the lower of your GCWR-based figure and the manufacturer tow rating.
Towing capacity, defined
Your available towing capacity is the most trailer weight your vehicle can pull without exceeding its GCWR, the combined limit for truck plus trailer. It shrinks as you add passengers and cargo, because everything rides against the same combined rating. Tongue weight, the download on the hitch, should sit around 10-15% of the loaded trailer for stable handling.
The formula
available capacity = GCWR − (curb weight + passengers + cargo)
safe max = min(available capacity, manufacturer tow rating)
target tongue weight = trailer weight × 12%
safe max = min(available capacity, manufacturer tow rating)
target tongue weight = trailer weight × 12%
Worked example
With a 15,000 lb GCWR, a 6,000 lb truck and 900 lb of people and gear, available capacity = 15,000 − 6,900 = 8,100 lb. A 7,000 lb trailer uses about 86% of that, within limits but above the 80% comfort zone. Aim for a tongue weight near 7,000 × 12% = 840 lb.
Frequently asked questions
How do I calculate available towing capacity?
GCWR minus the loaded tow-vehicle weight (curb + passengers + cargo).
What is GCWR?
The max combined weight of fully loaded truck and trailer. Never exceed it.
What is tongue weight?
The hitch download, ideally 10-15% of loaded trailer weight.
Should I tow at 100% of capacity?
No, staying under about 80% preserves braking and handling.
Where do I find these numbers?
Owner's manual and door-jamb sticker; weigh at a CAT scale to confirm.