# Road trip vehicle load calculator - Human page: https://happytails.ai/en/calculators/road-trip-vehicle-load-calculator/ - Markdown: https://happytails.ai/en/calculators/road-trip-vehicle-load-calculator.md - Structured JSON: https://happytails.ai/agents/en/calculators/road-trip-vehicle-load-calculator/index.json - Visibility: public ## Tool capabilities | Property | Value | | --- | --- | | Tool ID | `road-trip-vehicle-load-calculator` | | Category | calculators | | Implementation | Registered implementation. Registration alone is not a production-quality guarantee. | | Browser execution | Use the visible action or interactive controls. | | Browser processing | Browser; see tool notes for network behavior. | | HTTP API | Not callable through HTTP. | | Browser-agent interface | run_current_tool | ### Implementation notes Calculated on your device for up to 200 load rows and 100,000 characters. It compares your estimated loads with the ratings you enter; weigh the loaded vehicle to confirm. ### Inputs and settings Text input: Load list. Example or placeholder shown in the interface (not a validated fixture): ```text item, type, weight, quantity ``` One load per line. Type is occupant, cargo, roof or hitch; quantity is optional. Write weights without thousands separators. Up to 100,000 characters. Review the settings before running. | Setting | Meaning | Control type | Default | Constraints | | --- | --- | --- | --- | --- | | `massUnit` | Weight unit | select | "lb" | Allowed: lb, kg | | `payload` | Occupant and cargo capacity | number | 1100 | min=0 step=any | | `roofRating` | Roof load limit (optional) | number | "" | min=0 step=any | | `hitchRating` | Tongue weight rating (optional) | number | "" | min=0 step=any | | `trailer` | Trailer | select | "No trailer" | Allowed: No trailer, Trailer | | `trailerWeight` | Loaded trailer weight | number | 1500 | min=0 step=any | | `tongueMode` | Tongue weight from | select | "Percent of trailer weight" | Allowed: Percent of trailer weight, Measured tongue weight | | `tonguePercent` | Tongue weight share of trailer weight (%) | number | 10 | min=0 max=50 step=any | | `tongueWeight` | Measured tongue weight | number | 150 | min=0 step=any | | `towingRating` | Towing capacity (optional) | number | "" | min=0 step=any | ### Browser-agent workflow 1. Open the human page in a browser that supports WebMCP. 2. Discover the interface exposed by that page; use its actual schema. 3. Select files on the page first when the tool requires files. 4. Call `run_current_tool` with valid input and settings. 5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links. Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution. ### Planning specification One load per line, up to 200 rows and 100,000 characters; weights above 0 and up to 10,000 kg each, written without thousands separators, quantity 1 to 100; occupant and cargo capacity up to 20,000 kg, roof limit up to 1,000 kg, tongue weight rating up to 5,000 kg, trailer and towing capacity up to 50,000 kg, tongue share 0 to 50%. Calculated on your device; download a JSON report and a CSV of results. This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support. ### Complete machine-readable capability record ```json { "id": "road-trip-vehicle-load-calculator", "category": "calculators", "built": true, "requirements": "One load per line, up to 200 rows and 100,000 characters; weights above 0 and up to 10,000 kg each, written without thousands separators, quantity 1 to 100; occupant and cargo capacity up to 20,000 kg, roof limit up to 1,000 kg, tongue weight rating up to 5,000 kg, trailer and towing capacity up to 50,000 kg, tongue share 0 to 50%. Calculated on your device; download a JSON report and a CSV of results.", "implementation": { "fields": [ { "key": "massUnit", "label": "Weight unit", "value": "lb", "type": "select", "values": [ "lb", "kg" ] }, { "key": "payload", "label": "Occupant and cargo capacity", "value": 1100, "type": "number", "min": 0, "step": "any", "help": "From the tire and loading placard on the driver’s door pillar: the combined weight of occupants and cargo should never exceed this figure." }, { "key": "roofRating", "label": "Roof load limit (optional)", "value": "", "type": "number", "min": 0, "step": "any", "help": "The lower of the vehicle and roof rack limits. Leave empty to skip." }, { "key": "hitchRating", "label": "Tongue weight rating (optional)", "value": "", "type": "number", "min": 0, "step": "any", "help": "The lowest tongue weight rating of the vehicle, hitch and carrier. Leave empty to skip." }, { "key": "trailer", "label": "Trailer", "value": "No trailer", "type": "select", "values": [ "No trailer", "Trailer" ] }, { "key": "trailerWeight", "label": "Loaded trailer weight", "value": 1500, "type": "number", "min": 0, "step": "any", "showWhen": { "trailer": [ "Trailer" ] } }, { "key": "tongueMode", "label": "Tongue weight from", "value": "Percent of trailer weight", "type": "select", "values": [ "Percent of trailer weight", "Measured tongue weight" ], "showWhen": { "trailer": [ "Trailer" ] } }, { "key": "tonguePercent", "label": "Tongue weight share of trailer weight (%)", "value": 10, "type": "number", "min": 0, "max": 50, "step": "any", "help": "Use the figure from your trailer and vehicle manuals. 10% is an editable example.", "showWhen": { "trailer": [ "Trailer" ], "tongueMode": [ "Percent of trailer weight" ] } }, { "key": "tongueWeight", "label": "Measured tongue weight", "value": 150, "type": "number", "min": 0, "step": "any", "showWhen": { "trailer": [ "Trailer" ], "tongueMode": [ "Measured tongue weight" ] } }, { "key": "towingRating", "label": "Towing capacity (optional)", "value": "", "type": "number", "min": 0, "step": "any", "help": "From the owner’s manual. Leave empty to skip.", "showWhen": { "trailer": [ "Trailer" ] } } ], "registrationFamily": "vehicle-and-cycling", "input": true, "live": false, "presentation": "metrics", "inputMaxLength": 100000, "inputErrorCode": "VEHICLE_AND_CYCLING_TOO_LONG", "note": "Calculated on your device for up to 200 load rows and 100,000 characters. It compares your estimated loads with the ratings you enter; weigh the loaded vehicle to confirm.", "experience": { "automatic": false, "single": false, "inputMaxLength": 100000, "inputMode": "text", "label": "Load list", "placeholder": "item, type, weight, quantity", "help": "One load per line. Type is occupant, cargo, roof or hitch; quantity is optional. Write weights without thousands separators. Up to 100,000 characters. Review the settings before running.", "action": null }, "mode": "explicit", "interactive": false }, "execution": "Browser interface", "api": null, "browser_agent": { "supported": true, "name": "run_current_tool", "discovery": "WebMCP on the human page in a supporting browser", "verification": "See audit/API-AUDIT.md; availability is not verification" } } ``` ## Page guide List the people, luggage, roof and hitch loads for a trip and compare the estimated totals with the ratings for your vehicle. Add a trailer to include its tongue weight. How can we improve this tool? Report a problem or share an idea. Please leave out private information. Your message and the tool name go to our team via PostHog. ### How to use Road trip vehicle load calculator 1. Enter the occupant and cargo capacity from the tire and loading placard on the door pillar. 2. List each load on its own line: item, type (occupant, cargo, roof or hitch), weight and an optional quantity. 3. Add the roof load limit and tongue weight rating, and the trailer weight and towing capacity if you tow. 4. Review the capacity left for each rating, then download the JSON report or CSV. ## Useful next steps - [Fuel cost calculator](https://happytails.ai/en/calculators/fuel-cost-calculator/) ([Markdown](https://happytails.ai/en/calculators/fuel-cost-calculator.md)) - [Trip Budget Calculator](https://happytails.ai/en/calculators/trip-budget-calculator/) ([Markdown](https://happytails.ai/en/calculators/trip-budget-calculator.md)) - [Weight](https://happytails.ai/en/unit-converters/weight/) ([Markdown](https://happytails.ai/en/unit-converters/weight.md)) ## Occupant and cargo capacity US vehicles carry a placard stating that the combined weight of occupants and cargo should never exceed a figure. The steps in 49 CFR 575.6(a)(5) (checked 16 October 2026) subtract the driver and passengers from that figure to find what is left for cargo and luggage: 1,400 lb minus five 150 lb passengers leaves 650 lb. This tool follows the same arithmetic and adds roof and hitch loads. ### Roof, hitch and trailer Roof rows count against the roof load limit and include the rack or box itself. Hitch rows, such as a bike carrier, and the trailer tongue weight count against the tongue weight rating. The same regulation notes that trailer load transfers to the vehicle, so tongue weight also uses occupant and cargo capacity. Tongue weight is either measured or a share of the loaded trailer weight; use the figure from your trailer and vehicle manuals. ### Limits Up to 200 load rows and 100,000 characters, single weights up to 10,000 kg, quantities up to 100 and ratings up to 20,000 kg for the placard, 1,000 kg for the roof, 5,000 kg for the hitch and 50,000 kg for towing. This is an arithmetic estimate, not a weighing or a safety check: axle ratings, gross combined weight and local rules are not checked. Weigh the loaded vehicle at a public scale to confirm. Unit conversions use NIST SP 811 factors.