Motorhome Payload Calculator

GVW (Gross Vehicle Weight) is the maximum weight your motorhome is legally allowed to be when fully loaded — including passengers, fuel, water, gas, and all your gear. It’s set by the manufacturer and shown on the vehicle’s VIN plate. Go over it and you’re driving illegally, even if the overload isn’t obvious.

Check the manufacturer’s VIN plate (usually in the driver’s door frame, engine bay, or chassis), your V5C logbook (look for “Revenue Weight”), or the original vehicle handbook. If in doubt, weigh the van at a public weighbridge.

A C1 licence lets you drive vehicles between 3,500 kg and 7,500 kg. If you passed your car test before 1 January 1997, you likely already have C1 entitlement on your licence. If you passed after that date, your licence is capped at 3,500 kg and you’ll need to pass a separate C1 test to drive a heavier motorhome.

No — not legally. If your licence only covers category B (up to 3,500 kg) and your motorhome’s MAM exceeds that, you must either downplate the vehicle to 3,500 kg (where possible) or take the C1 test before driving it.

Payload is how much weight you can safely add to your motorhome before hitting its MAM. Calculate it as: MAM minus Mass in Service (the empty-van figure on the UK V5; handbooks often call this MIRO). What’s left is your payload for passengers, water, gas, and belongings.

It varies by model and can be surprisingly low — often 300–500 kg once passengers and habitation equipment are factored in. Check your V5 for Mass in Service and MAM, or use our calculator above to work it out instantly.

Maximum Authorised Mass (MAM) is the heaviest your van is allowed to be on the road (the plated weight). It’s the same figure as GVW — manufacturers and official documents just use different terms for it.

None, practically speaking — they’re the same value. MTPLM (Maximum Technically Permissible Laden Mass) is the EU/technical term; MAM is the term used in UK licensing law. Motorhome brochures often list MTPLM, while your licence category depends on MAM.

Mass in Service is the empty-van figure on the UK V5. Handbooks often call the same idea MIRO (Mass in Running Order). It usually includes the driver (75 kg), oils, 90% fuel and standard tools. Fresh water is normally assumed empty on UK motorhomes, so a full tank is extra payload. Always check your V5 or handbook, because converters differ.

A typical conversion leaves only 300–500 kg after Mass in Service. Two adults, a full 90–120 L water tank, gas bottles, a leisure battery, an awning and two bikes can use that allowance before food, clothes or a dog are added. That is why 3.5 t vans feel tight and why a weighbridge visit is worthwhile.

Mass in Service from the V5 usually assumes a 75 kg driver. Enter your real weight — only the extra kilograms above 75 are added. Extra adults, children and pets are additional. If you enter a weighbridge empty weight of the van only, the full driver weight is added.

Water weighs 1 kg per litre and is usually empty in Mass in Service, so a full tank is extra. Diesel is about 0.84 kg per litre. Mass in Service already includes about 90% fuel, so this page only adds the top-up (about 8 kg on a 90 L tank at 100%), unless you are working from a weighed empty van. A 9 kg propane bottle weighs around 18–19 kg when full because of the steel cylinder.

Yes. Exceeding MAM can mean a roadside prohibition, a fine, points, and invalid insurance if you are involved in a collision. Overloaded axles are a separate offence even when the total is under MAM. There is no “small margin” in law — stay under the plated figures.

This is an estimate. Mass in Service and handbook MIRO figures are often optimistic, converters vary, and household kit is easy to under-count. Use the calculator to see where weight is coming from, then confirm on a calibrated weighbridge — ideally per axle — before a trip. The printed results are not a legal document.

Yes. A UK plate lookup fills make and year, plus the DVLA revenue weight (often the plated MAM). DVLA does not supply model or Mass in Service. Model stays blank unless MOT history gives an exact van-maker model — coachbuilts such as Hymer are not filled with Ducato. Pick the platform from the list, and enter an empty weighbridge ticket or Mass in Service from the V5. You can also choose make, model and year to apply typical catalogue figures (often 3.5 t examples). Always confirm weights on the VIN plate and handbook.

Under MAM but over on an axle is still a fail / roadside risk.

Plate axle ratings are limits, not today’s load. Enter front and rear kg from a weighbridge ticket — Empty for the base van, Loaded for a roadside check (Loaded is the default). We only pass or fail when both the plate limits and those ticket weights are present. We never invent an axle split from people or kit. A rear axle over the plate is a fail even if total MAM is OK.

The sticker inside the driver’s door is for the original tyres. If you fitted a different size, use the Tyres tool with your front and rear axle weights and the new sidewall. See Sources we use on that page for the brands covered today. If your size is not listed, that page refuses a number. The tyre maker and a fitter still win.