Towing Payload Calculator
This towing payload calculator determines how much trailer weight you can safely tow by subtracting the vehicle curb weight, cargo weight, and passenger weight from the Gross Combined Weight Rating (GCWR). GCWR is the maximum total weight of everything combined: tow vehicle, all passengers, all cargo, and the trailer with its load. Staying within GCWR is a legal and safety requirement. The SAE J2807 towing standard, adopted by most major truck and SUV manufacturers, defines how these ratings are tested and published.
Towing capacity formula
Loaded Vehicle Weight = Curb Weight + Cargo + Passengers Max Trailer Weight = GCWR - Loaded Vehicle Weight
This is the SAE J2807 approach. Always also check that your actual trailer tongue weight does not exceed the hitch rating (typically 10-15% of trailer weight), and that actual vehicle weight does not exceed GVWR. All three limits must be respected.
Towing safety checklist
- Verify the GCWR and GVWR on the door jamb sticker, not from internet estimates.
- Weigh the loaded tow vehicle at a certified scale before long trips to confirm you are within limits.
- Check trailer brake requirements: most states require trailer brakes on trailers over 3,000 lb, and all trailers over 5,000 lb.
- Ensure mirrors provide view of both sides of the trailer for the full length. Towing mirrors may be legally required.
- Allow extra stopping distance: a truck plus trailer at maximum weight requires significantly more distance to stop than the unladen vehicle.
Frequently asked questions
What is GCWR?
Gross Combined Weight Rating (GCWR) is the maximum allowable total weight of the towing vehicle plus the trailer and all cargo. It is set by the vehicle manufacturer and must never be exceeded. Exceeding GCWR stresses the drivetrain, brakes, and frame beyond their design limits.
What is GVWR and how is it different from GCWR?
GVWR (Gross Vehicle Weight Rating) is the maximum total weight of the tow vehicle alone, including passengers and cargo. GCWR includes the trailer as well. Both ratings must be respected: you can hit GVWR without reaching GCWR if pulling a light trailer, or stay under GVWR while the trailer pushes you over GCWR.
What is the SAE J2807 towing standard?
SAE J2807 is the industry standard for towing capacity testing and labeling, adopted by most major manufacturers. It specifies a defined test procedure including a 12% grade hill climb, temperature conditions, and load definitions, ensuring that published tow ratings reflect repeatable, standardized performance.
How much of my trailer weight should be on the hitch?
Tongue weight should be 10-15% of total trailer weight for most trailers. Too little tongue weight causes trailer sway; too much overloads the rear axle of the tow vehicle and lifts the front axle, reducing steering control. Weight distribution hitches redistribute tongue weight across all axles.
Does the engine size affect towing capacity?
Yes, but the limiting factor is often the transmission cooling, frame strength, axle rating, and brake capacity rather than raw engine power. Higher axle ratios (numerically larger, like 3.73 vs 3.08) provide more torque multiplication for towing but increase engine RPM at highway speed.
Official sources
- SAE International J2807: sae.org - Performance Requirements for Determining Tow-Vehicle Gross Combination Weight Rating.
- NHTSA: nhtsa.gov - vehicle weight ratings and safety regulations.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.