{
  "id": "towing-capacity",
  "version": "94007531c854",
  "status": "published",
  "name": "Towing Capacity Calculator",
  "question": "What is my towing capacity?",
  "summary": "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.",
  "category": "everyday-life",
  "subcategory": "travel-and-fuel",
  "url": "https://www.acalculator.org/everyday-life/towing-capacity-calculator",
  "markdown": "https://www.acalculator.org/everyday-life/towing-capacity-calculator.md",
  "kind": "function",
  "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."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "gcwr": {
        "title": "GCWR",
        "description": "Gross combination weight rating: the most the loaded vehicle and loaded trailer may weigh together.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 1,
        "maximum": 100000
      },
      "gvwr": {
        "title": "GVWR",
        "description": "Gross vehicle weight rating: the most the loaded vehicle may weigh, tongue weight included.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 1,
        "maximum": 100000
      },
      "curb": {
        "title": "Curb weight",
        "description": "The vehicle empty, with full fuel, oil and coolant.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 1,
        "maximum": 100000
      },
      "load": {
        "title": "People and cargo",
        "description": "Everyone riding, the driver included, plus cargo and accessories in the vehicle.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0,
        "maximum": 100000
      },
      "trailer": {
        "title": "Loaded trailer weight",
        "description": "The trailer and everything loaded on it.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0,
        "maximum": 100000
      },
      "tongue": {
        "title": "Tongue weight share",
        "description": "The share of the trailer weight on the hitch: 10% to 15% for a conventional trailer, or the share in your manual.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 100
      }
    }
  },
  "outputs": {
    "maxTrailer": {
      "label": "Heaviest trailer by GCWR",
      "description": "GCWR − (curb weight + people and cargo).",
      "format": "quantity",
      "unit": "lb"
    },
    "payload": {
      "label": "Payload capacity",
      "description": "GVWR − curb weight.",
      "format": "quantity",
      "unit": "lb"
    },
    "payloadLeft": {
      "label": "Payload left",
      "description": "GVWR − curb weight − people and cargo − tongue weight.",
      "format": "quantity",
      "unit": "lb"
    },
    "tongueWeight": {
      "label": "Tongue weight",
      "description": "Loaded trailer weight × tongue weight share.",
      "format": "quantity",
      "unit": "lb"
    },
    "combined": {
      "label": "Combined weight",
      "description": "Curb weight + people and cargo + loaded trailer weight.",
      "format": "quantity",
      "unit": "lb"
    },
    "gcwrLeft": {
      "label": "Room under GCWR",
      "description": "GCWR − combined weight.",
      "format": "quantity",
      "unit": "lb"
    },
    "verdict": {
      "label": "This trailer",
      "description": "Whether the trailer fits under both the GCWR and the GVWR.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "gcwr": 6350.293180000001,
      "gvwr": 3175.1465900000003,
      "curb": 2267.96185,
      "load": 272.155422,
      "trailer": 2721.55422,
      "tongue": 10
    },
    "outputs": {
      "maxTrailer": 3810.175908,
      "payload": 907.18474,
      "payloadLeft": 362.873896,
      "tongueWeight": 272.155422,
      "combined": 5261.671492,
      "gcwrLeft": 1088.621688,
      "verdict": "fits under the GCWR and the GVWR"
    },
    "text": "By its GCWR, your vehicle can tow a trailer of up to 8,400 lb. This trailer fits under the GCWR and the GVWR."
  },
  "examples": [
    {
      "given": {
        "gcwr": 6350.293180000001,
        "gvwr": 3175.1465900000003,
        "curb": 2267.96185,
        "load": 272.155422,
        "trailer": 2721.55422,
        "tongue": 10
      },
      "expect": {
        "maxTrailer": 3810.175908,
        "payload": 907.18474,
        "payloadLeft": 362.873896,
        "tongueWeight": 272.155422,
        "combined": 5261.671492,
        "gcwrLeft": 1088.621688,
        "verdict": "fits under the GCWR and the GVWR"
      },
      "source": "hand calculation in content.mdx: 14,000 − 5,600 = 8,400 lb; 7,000 − 5,000 − 600 − 600 = 800 lb; 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; GVWR the loaded weight of a single 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)"
    },
    {
      "given": {
        "gcwr": 4989.516070000001,
        "gvwr": 2721.55422,
        "curb": 2177.243376,
        "load": 362.873896,
        "trailer": 2721.55422,
        "tongue": 12
      },
      "expect": {
        "maxTrailer": 2449.398798,
        "payloadLeft": -145.14955840000002,
        "gcwrLeft": -272.155422,
        "verdict": "is over the GCWR and the GVWR"
      },
      "source": "hand calculation in content.mdx: 11,000 − 5,600 = 5,400 lb; 6,000 − 5,600 − 720 = −320 lb; 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; GVWR the loaded weight of a single 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)"
    },
    {
      "given": {
        "gcwr": 7000,
        "gvwr": 3000,
        "curb": 2200,
        "load": 300,
        "trailer": 2000,
        "tongue": 10
      },
      "expect": {
        "maxTrailer": 4500,
        "payload": 800,
        "payloadLeft": 300,
        "gcwrLeft": 2500,
        "verdict": "fits under the GCWR and the GVWR"
      },
      "source": "hand calculation in content.mdx: 7,000 − 2,500 = 4,500 kg; 3,000 − 2,500 − 200 = 300 kg; 49 CFR 571.3: GCWR is the value specified by the manufacturer as the loaded weight of a combination vehicle; GVWR the loaded weight of a single 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)"
    }
  ],
  "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)"
  ],
  "related": [
    "tongue-weight",
    "gas-mileage"
  ],
  "changelog": []
}