Will your build fit your van’s payload?

GVWR, curb weight and payload, in plain words

• GVWR (gross vehicle weight rating) is the most your vehicle is allowed to weigh, fully loaded. The maker sets it, and it’s printed on the sticker in the driver’s door frame.
• Curb weight is the empty vehicle, ready to drive: standard equipment and a full tank of fuel, with no people and no cargo.
• Payload is what’s left for everything you add. In the US it’s worked out as payload = GVWR − curb weight. Your build, water, gear, pets and every person on board, the driver included, come out of it.
• GAWR (gross axle weight rating) is the limit for each axle. You can be under GVWR and still overload the rear axle, so a heavy rear bathroom or a tyre carrier needs care.

In the UK and EU, check how your figures are defined. The “mass in running order” used there already includes a driver and fuel, so a European payload figure isn’t worked out the same way as a US one.

How this works

• Water = tank volume × 8.34 lb per US gallon (or about 1 kg per litre). Every tank is counted full.
• Total added = build + water + propane + people × weight each + pets + gear, rounded up.
• Payload left = (GVWR − curb weight) − total added, rounded down. If you weighed the built van, payload left = (GVWR − scale weight) − what wasn’t on the scale.
• Percentage used = total added ÷ payload. The warning shows at 90% or more.

The model figures come from manufacturer and body-builder spec sheets and measured conversion guides, collected in September 2026. They’re approximate for a base cargo van; some are marked estimated, and skoolies, box trucks, trailers and truck beds use typical values. The starting example is a 2019+ Sprinter 144″ high roof, a medium example build, 20 gal fresh and 10 gal grey water, one 20-lb propane cylinder, two people at 185 lb each (close to the average of US men and women, from CDC data) and 300 lb of gear. The example build weights are illustrations to edit, not measured averages.

Weigh your van: it’s the only number that counts

• Read the sticker on the driver’s door frame. It lists your GVWR and axle ratings, and the tire placard gives the most that people and cargo together should weigh.
• Weigh the van at a public truck scale, such as a CAT Scale at many truck stops. Park with one axle on each platform to see each axle’s weight.
• Weigh it ready for a trip: full water, propane, gear and everyone who travels. Then compare with your GVWR and each axle rating.
• Too heavy? Water is the easiest weight to drop: drive with less in the tank and fill up near camp.

This is a planning estimate, not a safety certification. Overloading affects braking, steering, tyres and insurance. For heavy builds or changes to suspension and axles, talk to a qualified upfitter or the vehicle maker.

Sources

• 49 CFR 571.3: definition of gross vehicle weight rating (GVWR)
• 40 CFR 86.1803-01: definition of curb weight
• 49 CFR 571.110 (FMVSS 110): the tire and loading placard on the driver’s door pillar, “The combined weight of occupants and cargo should never exceed…”
• EU Regulation 1230/2012: masses and dimensions of motor vehicles (“mass in running order”)
• USGS Water Science School: water density (a US gallon weighs about 8.34 lb)
• Worthington Enterprises portable cylinder sheet: 20 lb steel cylinder, 16.6 lb tare, 4.7 gal
• Battle Born BB10012 spec sheet: 100 Ah 12 V LiFePO₄ battery, 31 lb
• CDC FastStats: body measurements (average US adult weights)
• CAT Scale: find a certified truck scale