Campervan MTPLM Calculator
Avoid Overloading
Easily calculate the total weight and payload of your conversion with our free MTPLM calculator.
Manage your payload, avoid DVSA axle overloading fines, and keep your UK build legally compliant!
🚐 The Base Van
Select your model or enter the details from your vehicle logbook (V5C) for an unladen van before conversion.
Why Is Your "Weight Budget" the Biggest Challenge of a Campervan Conversion?
When converting a panel van into a campervan, we immediately think about the financial budget. Yet there is another resource that is just as limited and just as crucial: your weight budget, in other words, your payload.
The MTPLM (Maximum Technically Permissible Laden Mass) is the legal weight limit set by your vehicle manufacturer (typically 3,500 kg for a large van driven on a standard UK Category B driving licence). Exceeding this limit is one of the most common and serious mistakes in the vanlife world. Keeping track of the weight of every sheet of timber and every item of equipment using an MTPLM calculator is an essential step towards a successful conversion.
The Dangers of an Overloaded Campervan (Exceeding the MTPLM)
Converting your van without keeping track of its weight means exposing yourself to three major risks:
- DVLA & Weighbridge Non-Compliance: If you apply for a DVLA V5C body-type change or insurance reclassification, you will be required to provide an official weighbridge ticket for your completed vehicle with full fuel and water tanks. If the weight exceeds the MTPLM, reclassification is refused.
- A Serious Road Safety Hazard: Your van's chassis, suspension, and braking system are designed to handle a specific maximum weight. Overloading increases braking distances significantly and makes the vehicle unstable when cornering or emergency braking.
- DVSA Roadside Fines & Impounding: UK DVSA enforcement officers carry out regular roadside spot checks at weighbridges. Overloading results in immediate fixed penalty notices (£100–£300+ fines), penalty points, and a prohibition notice preventing the vehicle from moving until weight is shed. In an accident, an overloaded vehicle invalidates your insurance.
The "Heavy Hitters" of a Campervan Conversion
Using the VanLogic simulator helps you realise just how quickly certain items can eat into your available payload:
- Fresh Water: It's easy to forget that 100 litres of water weigh exactly 100 kg. Add a full grey water tank, and your plumbing system can take a massive chunk out of your payload.
- Your Choice of Timber: This is where weight really mounts up. Building cabinetry from OSB, MDF, or solid pine is a costly mistake. Instead, prioritize lightweight furniture plywood such as poplar or okoumé.
- Passengers & Luggage: Mass in Running Order (MIRO) on your V5C logbook only accounts for a single 75 kg driver. If traveling with additional passengers, dogs, and gear, that weight directly eats into your remaining payload.
VanLogic Tip: Never target an exact 3,500 kg limit. Maintain a safety margin of at least 100 to 150 kg in your calculations to account for food, clothing, sports gear, and holiday souvenirs on the road!
Staying within your MTPLM is essential, but do you know how to distribute weight across axles to pass weighbridge checks? Discover our complete weight and reclassification guide.
FAQ: Weight & Payload in a Campervan Conversion
What is the MTPLM on a van's registration document?
The MTPLM (Maximum Technically Permissible Laden Mass), also referred to as Gross Vehicle Weight (GVW) or Revenue Weight, is the maximum legal weight your vehicle must never exceed on public roads. For standard vans driven on a UK Category B licence (Ducato, Master, Sprinter), this limit is 3,500 kg (3.5 tonnes). It can be found in section 4 (Revenue Weight) or Line [Y] of your UK V5C logbook.
What is the difference between MTPLM and Unladen Weight (MIRO)?
Mass in Running Order (MIRO), shown on your V5C logbook or manufacturer spec sheet, represents the weight of the base vehicle in unladen condition. It includes the standard chassis, oil/coolant, a 90% full fuel tank, and a standard 75 kg allowance for the driver. The difference between MTPLM (e.g. 3,500 kg) and MIRO (e.g. 2,100 kg) gives you your available "payload" (1,400 kg).
What is payload in a campervan?
Payload is your remaining weight allowance for the entire build. It is the total weight of everything added to the base van: sound deadening, insulation, timber framing, cabinetry, appliances, leisure batteries, full water tanks, luggage, and extra passengers.
What happens if you exceed the MTPLM in the UK?
If stopped by the DVSA at a roadside weighbridge, exceeding your MTPLM results in immediate fixed penalty fines (£100 to £300+ depending on the percentage overloaded) and a prohibition notice preventing you from driving until weight is removed. Mechanically, overloading puts dangerous strain on axles, tyres, and brakes, and will invalidate your motor insurance policy in the event of an accident.
Is the MTPLM checked during campervan reclassification or inspections?
Yes. If applying for DVLA V5C body-type reclassification or specialist campervan insurance, you may be required to provide an official weighbridge certificate detailing individual front axle, rear axle, and total gross vehicle weight. The vehicle must be weighed with full fuel and water reserves to confirm it remains safely under 3,500 kg.
Which timber should I choose to convert a van without exceeding the MTPLM?
To preserve payload, lightweight poplar or okoumé plywood is the industry standard. It is significantly lighter than standard hardwood ply and far lighter than OSB or MDF. A proven approach is using 12mm–15mm lightweight ply for structural cabinetry and floor sub-base, and 5.5mm ply for wall and ceiling cladding.
Are passengers included when calculating payload?
Yes! While MIRO accounts for a 75 kg driver allowance, every additional passenger traveling with you directly reduces your available payload. Traveling with a partner, two children, or pets can easily add 150 kg to 250 kg to your total vehicle weight.
Are water and fuel included in the unladen weight?
The vehicle's unladen weight (MIRO) includes a 90% full fuel tank. However, fresh water, waste water, and LPG/gas tanks added during your conversion are NOT included. Because 1 litre of fresh water weighs exactly 1 kg, filling a 100-litre fresh water tank immediately adds 100 kg to your payload.
Which panel van offers the best payload capacity?
The Fiat Ducato (and its Peugeot Boxer / Citroën Relay siblings) is renowned in the UK for offering the highest usable payload in the 3.5-tonne class due to its lightweight unibody chassis construction. Heavy-duty rear-wheel-drive platforms like the Mercedes Sprinter or Iveco Daily are heavier unladen, leaving less payload margin for interior timberwork.
How do I weigh my van once the conversion is finished?
You can use a local public weighbridge, municipal council recycling depot, or agricultural merchant. Drive onto the bridge to get your total gross weight, then isolate the front and rear axles individually to ensure neither axle limit is exceeded. Always request an official stamped weight ticket for your records.
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