acalculator

What is my towing capacity?

Type your vehicle's ratings, its curb weight, what you carry in it, and the trailer. The towing capacity calculator shows the heaviest trailer the GCWR allows and whether this trailer fits under both ratings.

Your numbers

Units
Heaviest trailer by GCWR
8,400 lb

By its GCWR, your vehicle can tow a trailer of up to 8,400 lb. This trailer fits under the GCWR and the GVWR.

Payload capacity
2,000 lb
Payload left
800 lb
Tongue weight
600 lb
Combined weight
11,600 lb
Room under GCWR
2,400 lb
This trailer
fits under the GCWR and the GVWR

Heaviest trailer by GCWR: 8,400 lb. By its GCWR, your vehicle can tow a trailer of up to 8,400 lb. This trailer fits under the GCWR and the GVWR.

How to calculate

Computes how heavy a trailer a vehicle can tow from its GCWR, curb weight and load, the payload left under its GVWR after the tongue weight, and whether a trailer fits both ratings.

Example with the default inputs (GCWR 14,000 lb, GVWR 7,000 lb, Curb weight 5,000 lb, People and cargo 600 lb, Loaded trailer weight 6,000 lb, Tongue weight share 10%): By its GCWR, your vehicle can tow a trailer of up to 8,400 lb. This trailer fits under the GCWR and the GVWR.

Method: Heaviest trailer = GCWR − (curb weight + people and cargo); payload = GVWR − curb weight; payload left = payload − people and cargo − trailer × tongue share; room under GCWR = GCWR − (curb + people and cargo + trailer).

  • The ratings are the manufacturer’s, from the door-jamb label or the owner’s manual.
  • The vehicle’s own tow rating and hitch rating can be lower than the GCWR gives; the lowest limit applies.
  • The tongue weight counts toward the vehicle’s payload, as it presses on the hitch.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. GCWR 14,000 lb, GVWR 7,000 lb, Curb weight 5,000 lb, People and cargo 600 lb, Loaded trailer weight 6,000 lb, Tongue weight share 10% gives Heaviest trailer by GCWR 8,400 lb, Payload capacity 2,000 lb, Payload left 800 lb, Tongue weight 600 lb, Combined weight 11,600 lb, Room under GCWR 2,400 lb, This trailer fits under the GCWR and the GVWR.Source: 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; curb weight the vehicle with standard equipment and full fuel, oil and coolant, https://www.law.cornell.edu/cfr/text/49/571.3 (retrieved 2026-10-18)
  2. GCWR 11,000 lb, GVWR 6,000 lb, Curb weight 4,800 lb, People and cargo 800 lb, Loaded trailer weight 6,000 lb, Tongue weight share 12% gives Heaviest trailer by GCWR 5,400 lb, Payload left −320 lb, Room under GCWR −600 lb, This trailer is over the GCWR and the GVWR.Source: 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; curb weight the vehicle with standard equipment and full fuel, oil and coolant, https://www.law.cornell.edu/cfr/text/49/571.3 (retrieved 2026-10-18)
  3. GCWR 15,432 lb, GVWR 6,614 lb, Curb weight 4,850 lb, People and cargo 661.4 lb, Loaded trailer weight 4,409 lb, Tongue weight share 10% gives Heaviest trailer by GCWR 9,921 lb, Payload capacity 1,764 lb, Payload left 661 lb, Room under GCWR 5,512 lb, This trailer fits under the GCWR and the GVWR.Source: 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; curb weight the vehicle with standard equipment and full fuel, oil and coolant, https://www.law.cornell.edu/cfr/text/49/571.3 (retrieved 2026-10-18)

How it works

Every weight is converted to the same unit first (1 lb = 0.45359237 kg exactly).

  • Loaded vehicle = curb weight + people and cargo
  • Heaviest trailer by GCWR = GCWR − loaded vehicle
  • Payload capacity = GVWR − curb weight
  • Tongue weight = loaded trailer weight × tongue weight share ÷ 100
  • Payload left = GVWR − loaded vehicle − tongue weight
  • Combined weight = loaded vehicle + loaded trailer weight
  • Room under GCWR = GCWR − combined weight
  • This trailer is "over the GCWR" when the room under GCWR is below 0, "over the GVWR (payload)" when the payload left is below 0, "over the GCWR and the GVWR" when both are, and "fits under the GCWR and the GVWR" otherwise (exactly 0 fits).

Payload left and room under GCWR can be negative: a negative value is how far over the rating you are. The heaviest trailer is never negative (see below).

Exact arithmetic. Each weight and percent is read as the exact decimal you typed, in its unit, so every result is exact.

Rounding. Weights show in pounds (kilograms in Metric) or in the unit typed in the GCWR box, as whole numbers, rounded half up.

When there is no answer. If the curb weight is equal to or more than the GVWR, or the GVWR is equal to or more than the GCWR, the page gives no answer. If the curb weight plus people and cargo is more than the GCWR, the loaded vehicle alone is over its GCWR and can tow no trailer: the page gives no answer and says so. At exactly the GCWR, the heaviest trailer is 0.

Assumptions

  • The ratings are the manufacturer's for your exact vehicle.
  • The tongue weight counts toward payload. The default share is 10%, the low end of the common US guidance of 10 to 15% for a conventional trailer (Hyundai's manual). Kia's US manual caps it at 10% for its vehicles, and NSW Government in Australia gives about 5 to 10%. Type the share your manual gives.
  • The vehicle's tow rating, hitch rating and axle ratings are not part of this sum; the lowest limit applies.
  • GCWR, GVWR and curb weight are 1 to 100,000 kg; people and cargo and the trailer are 0 to 100,000 kg; the tongue share is 0% to 100%.

Worked examples by hand

A pickup: GCWR 14,000 lb, GVWR 7,000 lb, curb 5,000 lb, 600 lb of people and cargo, a 6,000 lb trailer, 10% tongue. Loaded vehicle 5,600 lb. Heaviest trailer: 14,000 − 5,600 = 8,400 lb. Payload: 7,000 − 5,000 = 2,000 lb. Tongue weight 6,000 × 10% = 600 lb, so payload left = 7,000 − 5,600 − 600 = 800 lb. Combined 11,600 lb, room under GCWR = 2,400 lb. The trailer fits.

A smaller SUV: GCWR 11,000 lb, GVWR 6,000 lb, curb 4,800 lb, 800 lb load, a 6,000 lb trailer, 12% tongue. Heaviest trailer: 11,000 − 5,600 = 5,400 lb. Tongue weight 720 lb; payload left = 6,000 − 5,600 − 720 = −320 lb. Combined 11,600 lb; room = 11,000 − 11,600 = −600 lb. The trailer is over both ratings.

Metric: GCWR 7,000 kg, GVWR 3,000 kg, curb 2,200 kg, 300 kg load, a 2,000 kg caravan, 10% tongue. Heaviest trailer: 7,000 − 2,500 = 4,500 kg. Payload 800 kg; payload left = 3,000 − 2,500 − 200 = 300 kg. Room under GCWR = 7,000 − 4,500 = 2,500 kg. It fits.

Other questions people ask

How do I calculate towing capacity?

Subtract the weight of the loaded vehicle from the gross combination weight rating (GCWR). A truck with a 14,000 lb GCWR, a 5,000 lb curb weight and 600 lb of people and cargo can pull up to 14,000 − 5,600 = 8,400 lb, if its own tow rating and hitch allow that much.

What is the difference between GCWR and GVWR?

The GVWR is the most the loaded vehicle alone may weigh. The GCWR is the most the loaded vehicle and loaded trailer may weigh together. Federal rules (49 CFR 571.3) define both as values the manufacturer sets.

What is payload, and why does the trailer use it?

Payload is GVWR minus curb weight: what the vehicle can carry. The trailer’s tongue weight presses on the hitch, so it counts as payload, along with passengers and cargo.

Where do I find my vehicle’s ratings?

The GVWR is on the label in the driver’s door jamb. The GCWR, curb weight and tow rating are in the owner’s manual or the maker’s towing guide for your exact model, engine and axle ratio.

Is the heaviest trailer by GCWR my tow rating?

Not always. The maker’s tow rating, the hitch rating and the tire and axle ratings can each be lower. Use the lowest of them. The page shows the GCWR limit for the load you typed.

Why does carrying more people lower the towing capacity?

Everything in the vehicle counts against the GCWR. Every 100 lb of passengers or gear is 100 lb less trailer you can pull, and it also uses payload the tongue weight needs.