Which Base Van for a Camper Conversion? Payload Compared

25.09.2026 · 10 min read

Reading time: approx. 8 minutes

Choosing the base vehicle is the one decision in the whole conversion you can never undo. A worktop that turned out too heavy can be swapped. A bed can be rebuilt. The van stays — and with it the payload you have left for everything else.

Most comparisons are about length, standing height and price. Weight comes last, even though it is the limit a conversion actually fails at: not on space, but on the weighbridge.

“3.5 tonnes” tells you nothing about payload

Ducato, Sprinter, Crafter, Transit and Master are all available as 3.5-tonne vans. The gross vehicle weight rating is identical for all five. What differs is the kerb weight — and payload is nothing more than the difference between the two.

Five panel vans in a length suitable for conversion, all rated at 3,500 kg. All figures from the ADAC vehicle catalogue, retrieved on 25 September 2026:

Vehicle (exact ADAC variant) Kerb weight (EU) Payload
Fiat Ducato 35 L3H2 140 Multijet3 (from 11/23) 2,200 kg 1,300 kg
Renault Master L3H2 3.5 t Blue dCi 170 Advance automatic (from 07/25) 2,200 kg 1,300 kg
VW Crafter 35 high roof, medium length, 2.0 TDI 4MOTION automatic (from 10/23) 2,223 kg 1,277 kg
Ford Transit 350 L3 2.0 EcoBlue Trend, RWD (from 03/24) 2,239 kg 1,261 kg
Mercedes Sprinter long, high roof, 3.5 t 317 CDI, RWD (from 02/24) 2,355 kg 1,145 kg

Between the first and the last row lie 155 kg. For comparison: in our conversion-weight article, all the furniture of a complete build — bed, kitchen block, overhead lockers, bench seat — comes to 133 kg in total. The gap between two base vehicles is bigger than all the furniture put together.

Important: every row names one specific variant, not a verdict on the brand. Engine, gearbox, drivetrain and roof height shift the kerb weight within the same model range more than the difference between two manufacturers does. The Crafter above is the all-wheel-drive version with a high roof and automatic gearbox — the heavy end of its range — and still comes out ahead of the Transit and the Sprinter. If you want a lighter Sprinter, look at standard roof, front-wheel drive and a manual gearbox.

The kerb weight in the brochure is not a promise

What the spec sheet calls “kerb weight” is a standardised figure: the mass in running order as defined by EU Implementing Regulation 2021/535 (until June 2022: 1230/2012). It includes all operating fluids, a tank filled to 90 % and a flat 75 kg for the driver — regardless of what you actually weigh.

Two consequences that are regularly missed:

First: the driver is already in there. Do not subtract a driver a second time from the payload, or you will talk yourself into being poorer than you are.

Second: a tolerance of ±5 % is legally permitted on that figure. On a 2,200 kg kerb weight that is 110 kg. A van listed with 1,300 kg of payload can therefore leave the dealership entirely legally with 1,190 kg, before a single board has been fitted. On top of that comes every factory option ordered with it.

Only one document is binding: your registration certificate part I. Field F.1 is the technically permissible maximum laden mass, field G the mass in running order. Payload is F.1 minus G. And more reliable than any paperwork: drive onto a public weighbridge once, with a full tank.

Why 155 kg is more than you can claw back while building

A self-build weighs 400 to 500 kg dry. That figure is not estimated: it is worked out component by component, every part backed by a manufacturer figure, in How much does a van conversion weigh? — which also shows how much reserve is left in each weight class. This article is about the other question: what are the 155 kg from the table actually worth?

A great deal, because on the building side 155 kg is expensive. In that same calculation, switching from heavy to light sheet material — throughout, across the whole vehicle — bought back 104 kg. You would have to replan your entire conversion in lighter material and still not reach what the choice of base vehicle would have handed you in a single afternoon.

The reverse holds too: leave 155 kg on the table when buying the van and you have to win them back in the furniture with compromises — thinner boards, open instead of closed build methods, less equipment. That is why this decision belongs at the start and not at the end.

Which material weighs what is covered in Material weight in a van conversion. If you already own a van and simply want to know what is left: Sprinter & Ducato: calculating payload and weight correctly.

Work out your payload in the browser — free, no sign-up

The rear axle usually runs out before the payload does

This is where the table above stops helping. Payload is a total. But a vehicle also has a permissible axle load at the front and one at the rear — and on many panel vans the two added together exceed the gross vehicle weight rating. Which means you can overload the rear axle while the total weight is still fine.

In a camper conversion that happens almost inevitably, because the heavy things sit at the back: bed, water tank, batteries, rear carrier. That is why VanLogic shows not only Payload Left, but converts every piece of furniture into a load on the Front Axle and the Rear Axle and reports “Rear axle overloaded!” the moment it tips over — even when there would still be payload left overall.

How the underlying leverage works is explained in How to calculate campervan axle load. Why the height of a load matters too, and not just its position along the vehicle, is covered in Centre of gravity and rollover risk.

Weight is not everything: will a bed fit crossways?

The second hard limit is interior width. A transverse bed saves half a metre of vehicle length — but only if enough is left between the panelling. And panelling costs a few centimetres on each side that never appear in the manufacturer’s spec sheet: what is printed there is the raw load compartment width.

The same goes for standing height. Between the raw figure and what remains after floor build-up and insulation there are easily several centimetres — enough to turn “standing upright” into “almost standing upright”.

You can check both before buying, without owning a vehicle:

3.5 tonnes — or more straight away?

With a category B driving licence you may currently drive vehicles up to 3.5 t maximum authorised mass. That is why almost every conversion aims at this limit.

According to the ADAC, the new 4th EU driving licence directive provides for category B holders to be allowed to drive motorhomes up to 4.25 t in future — although the directive requires training or a test for this. The ADAC does not name a concrete implementation date. So if you are planning today, plan with 3.5 t and treat anything above it as a bonus, not a commitment.

If 3.5 t is too tight for you, an uprating or a base vehicle in the next weight class is the cleaner route than a conversion that permanently runs at its limit. Both mean different licence rules and, depending on the country, different regulations — sort that out before you buy, not after.

What to check before buying — on the forecourt, not in the brochure

  1. The papers of that specific vehicle, not of the model. On a used van, read field F.1 and field G of the registration certificate part I. On a new one, ask for the binding order confirmation with the options list, not the catalogue.
  2. Ask about the options before you ask about the price. Tow bar, night heater, second battery, all-wheel drive, automatic gearbox, high roof: every factory extra comes off your payload, and no comparison table tells you by how much.
  3. Weigh it once, with a full tank. A public weighbridge costs a few euros and gives you the one number nobody can argue with. If the weighbridge allows it, weigh axle by axle — you then also see how much reserve the rear axle actually still has.
  4. Compare variants, not brands. Two vehicles from the same model range are easily more than a hundred kilos apart. Note down engine, gearbox, drivetrain and roof height for every offer — without those four details a payload figure is worthless.
  5. Calculate the conversion before the money moves. In VanLogic you pick the base vehicle under “Choose Vehicle Preset”, place your furniture in it, and immediately see the payload left and both axle loads. If it does not work out, two clicks switch you to the next vehicle — same furniture, new numbers. That is exactly why this step belongs before the purchase and not after.

And plan with reserve. A 100 kg buffer for small stuff, retrofits and whatever gets added in year two is not caution, it is experience.

And one more figure that counts before you buy: the seats. Motorhomes have a minimum payload that must stay free — 10 kg per seat and per metre of vehicle length, plus 75 kg for every passenger. A fourth registered seat therefore costs 85 kg of weight budget before a single board goes in. What that means for your vehicle is in Motorhome minimum payload.

Conclusion

The gross vehicle weight rating is identical across all the common 3.5-tonne vans — the payload is not. Between the five variants compared here lie 155 kg, and the choice of variant within a model range often weighs more than the choice of brand. On top of that sits the ±5 % tolerance on kerb weight that no brochure mentions.

The base vehicle sets your weight budget for the entire life of the conversion. It is the one number in this project you need to know before the first cut — and the one you can no longer change afterwards.

→ Pick a vehicle and calculate your build for free — vanlogic.app

Sources

All figures retrieved on 25 September 2026.

About VanLogic: VanLogic is a planning app for camper van self-builders. Every piece of furniture gets a shape, dimensions, material and build method — the weight is calculated automatically, never estimated manually, and feeds live into payload, axle loads and centre of gravity. Available for iOS and Android — and testable directly in your browser.