# What is my towing capacity?

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.

- Page: https://www.acalculator.org/everyday-life/towing-capacity-calculator
- JSON spec: https://www.acalculator.org/everyday-life/towing-capacity-calculator.json
- Version: 94007531c854

## Default answer

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.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| gcwr | GCWR | Gross combination weight rating: the most the loaded vehicle and loaded trailer may weigh together. |
| gvwr | GVWR | Gross vehicle weight rating: the most the loaded vehicle may weigh, tongue weight included. |
| curb | Curb weight | The vehicle empty, with full fuel, oil and coolant. |
| load | People and cargo | Everyone riding, the driver included, plus cargo and accessories in the vehicle. |
| trailer | Loaded trailer weight | The trailer and everything loaded on it. |
| tongue | Tongue weight share | The share of the trailer weight on the hitch: 10% to 15% for a conventional trailer, or the share in your manual. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| maxTrailer | Heaviest trailer by GCWR | GCWR − (curb weight + people and cargo). |
| payload | Payload capacity | GVWR − curb weight. |
| payloadLeft | Payload left | GVWR − curb weight − people and cargo − tongue weight. |
| tongueWeight | Tongue weight | Loaded trailer weight × tongue weight share. |
| combined | Combined weight | Curb weight + people and cargo + loaded trailer weight. |
| gcwrLeft | Room under GCWR | GCWR − combined weight. |
| verdict | This trailer | Whether the trailer fits under both 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).

## Assumptions

- 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.

## Worked examples

1. gcwr = 6,350.29318, gvwr = 3,175.14659, curb = 2,267.96185, load = 272.155422, trailer = 2,721.55422, tongue = 10% gives maxTrailer = 3,810.175908, payload = 907.18474, payloadLeft = 362.873896, tongueWeight = 272.155422, combined = 5,261.671492, gcwrLeft = 1,088.621688, verdict = 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 = 4,989.51607, gvwr = 2,721.55422, curb = 2,177.243376, load = 362.873896, trailer = 2,721.55422, tongue = 12% gives maxTrailer = 2,449.398798, payloadLeft = -145.149558, gcwrLeft = -272.155422, verdict = 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 = 7,000, gvwr = 3,000, curb = 2,200, load = 300, trailer = 2,000, tongue = 10% gives maxTrailer = 4,500, payload = 800, payloadLeft = 300, gcwrLeft = 2,500, verdict = 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).

## FAQ

### 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.

## Sources

- 49 CFR 571.3 Definitions (Federal Motor Vehicle Safety Standards): gross combination weight rating (GCWR), gross vehicle weight rating (GVWR), gross axle weight rating, curb weight. https://www.law.cornell.edu/cfr/text/49/571.3 (retrieved 2026-10-18)
- Hyundai owner’s manual, If You Decide to Pull a Trailer: tongue load 10–15% of the total trailer weight; never exceed the GVWR. https://ownersmanual.hyundai.com/full_webhelp/LX3/2026/en_US/topic_snf_hxj_x5b.html (retrieved 2026-10-18)
- Kia owner’s manual (KA4, 2024, US), If you do decide to pull a trailer: tongue weight at most 10% of the loaded trailer weight. https://ownersmanual.kia.com/full_webhelp/KA4/2024/en_US/topics/t00397.html (retrieved 2026-10-18)
- NSW Government, Towing a trailer or caravan: as a general rule, the vehicle should carry about 5 to 10% of the loaded trailer’s mass at the coupling. https://www.nsw.gov.au/driving-boating-and-transport/roads-safety-and-rules/vehicle-safety-and-compliance/towing-a-caravan (retrieved 2026-10-18)
- NIST SP 811 (2008), Appendix B: 1 lb = 0.45359237 kg exactly. https://www.nist.gov/pml/special-publication-811 (retrieved 2026-10-18)