Campervan Weight Limits & Payload UK: Complete GVW Guide for DIY Conversions
Your van has a maximum weight it can legally carry. Exceed it and you are driving illegally, invalidating your insurance, and risking a dangerous failure of brakes, tyres, or suspension.
I have weighed every van I built. The first was 200kg over its GVW. I had to strip half the conversion and rebuild with lighter materials. The second I designed around weight from day one — it passed the weighbridge with 150kg to spare.
This guide covers everything you need to know about campervan weights: GVW, axle loads, payload calculations, downplating, and where DIY builds most commonly go over.
Key Terms
| Term | Meaning |
|---|---|
| GVW (Gross Vehicle Weight) | The maximum allowable weight of the fully loaded vehicle |
| Kerb Weight | The weight of the empty vehicle (no passengers, no cargo, full fuel) |
| Payload | GVW minus kerb weight = how much you can carry |
| Axle Weight | The maximum weight allowed on each axle (front and rear) |
| Nose Weight | The maximum weight on the tow ball (for bike racks) |
| Downplating | Voluntarily reducing the GVW on the V5C (to reduce tax or MOT class) |
| MAM (Maximum Authorised Mass) | Same as GVW. Used on driver's licence categories. |
Where to Find Your Van's Weights
| Source | What It Tells You |
|---|---|
| V5C (logbook) | GVW in box F.1 (gross vehicle weight). Kerb weight in box G. |
| VIN plate (under bonnet or driver's door pillar) | GVW + front axle + rear axle weights |
| Manufacturer brochure | Kerb weight by model variant |
| Manufacturer handbook | Payload figures (often optimistic) |
Be aware: The kerb weight on the V5C is often the factory weight for a standard panel van. Your van may have gained weight through rust, previous repairs, or aftermarket accessories before you even started converting.
Payload: What You Actually Have
Payload varies significantly by van model and spec.
| Van | GVW | Kerb Weight | Payload |
|---|---|---|---|
| Ford Transit Custom 290 L2 | 2,900kg | 1,860kg | 1,040kg |
| Ford Transit Custom 310 L2 | 3,100kg | 1,900kg | 1,200kg |
| Ford Transit Custom 340 L2 | 3,400kg | 1,950kg | 1,450kg |
| VW Transporter T6.1 SWB 150PS | 3,000kg | 1,880kg | 1,120kg |
| VW Transporter T6.1 LWB 150PS | 3,080kg | 1,940kg | 1,140kg |
| Mercedes Sprinter 314 L2 | 3,500kg | 2,050kg | 1,450kg |
| Mercedes Sprinter 316 L3 | 3,500kg | 2,150kg | 1,350kg |
| Fiat Ducato 35 L2 | 3,500kg | 2,000kg | 1,500kg |
| Fiat Ducato 35 L3 | 3,500kg | 2,100kg | 1,400kg |
| Renault Trafic L2 145PS | 2,890kg | 1,720kg | 1,170kg |
Notes:
- GVW varies by model year — check your specific van's VIN plate
- The higher payload variants (Transit 340, Ducato 35) often have heavier-duty suspension
- Adding a pop-top roof, roof rack, or bike rack reduces your available payload
How Much Does a Conversion Weigh?
This is where most DIY builders get caught out. The conversion adds significant weight.
| Conversion Element | Typical Weight |
|---|---|
| Insulation (full van) | 20–35kg |
| Plywood lining (full van) | 40–60kg |
| Floor (12mm ply + vinyl) | 25–40kg |
| Bed frame + mattress | 30–60kg |
| Kitchen units + worktop | 30–50kg |
| Sink + tap + water pump | 3–5kg |
| Fresh water tank (empty) | 5–10kg |
| Fresh water (30L full) | 30kg |
| Grey water tank (empty) | 3–5kg |
| Grey water (20L full) | 20kg |
| Gas bottle (6kg full) | 12kg |
| Fridge (compressor 12V) | 12–20kg |
| Hob | 4–8kg |
| Leisure battery (100Ah LiFePO4) | 10–13kg |
| Leisure battery (100Ah AGM) | 25–28kg |
| Solar panels (2 × 200W) | 15–20kg |
| Diesel heater + tank | 8–12kg |
| Roof vent / Maxxfan | 5–8kg |
| Seat (single, with base) | 15–25kg |
| Seat (double bench, with base) | 30–50kg |
| Curtains / blinds / upholstery | 8–15kg |
| Total bare conversion | ~300–500kg |
Add for a Full-Time Setup
| Item | Weight |
|---|---|
| Two people | 120–180kg |
| Clothing, bedding, towels | 20–30kg |
| Food + cooking gear | 15–25kg |
| Tools + spares | 10–20kg |
| Bikes (2) + rack | 25–40kg |
| Water (30L) | 30kg |
| Camping chairs + table | 10–15kg |
| Electronics (laptop, tablet, camera) | 5–8kg |
| Total living load | ~235–360kg |
Combined Total
| Scenario | Conversion | Living Load | Total |
|---|---|---|---|
| Minimal weekender | 200kg | 100kg | 300kg |
| Full DIY build, couple, moderate gear | 400kg | 250kg | 650kg |
| Full build, two bikes, full water | 500kg | 350kg | 850kg |
| Professional build, heavy materials | 600kg+ | 300kg | 900kg+ |
Putting It All Together: Transit Custom 310 Example
| Item | Weight |
|---|---|
| GVW | 3,100kg |
| Minus kerb weight (L2 van) | −1,900kg |
| Available payload | 1,200kg |
| Minus conversion (full build, no bathroom) | −400kg |
| Minus two passengers | −150kg |
| Minus gear + water + gas | −100kg |
| Remaining | 550kg |
This looks fine. But add a bathroom (+100kg), two bikes (+40kg), and a few full water tanks (+30kg), and you are at 380kg remaining. Still fine.
The problem comes when:
- The kerb weight on the V5C is wrong (common — they list the lightest variant)
- You use heavy materials (18mm ply instead of 9mm + ribbing)
- You fill both water tanks (60L = 60kg)
- You have a workshop, tools, and stock of spare parts onboard
The surprise 200kg: Many DIY builders do not weigh their van until they get pulled into a DVSA checkpoint. Suddenly the "plenty of room" payload is gone.
Axle Weights
Payload is not just about total weight — you must also check individual axle weights.
- Overloading the rear axle is common in campervans (the conversion is mostly behind the rear axle)
- Overloading the front axle is less common but happens if you fit a heavy pop-top or roof rack
- The axle weight limits are on the VIN plate
Cab-forward vs rear-heavy:
- A typical Transit Custom is 55% rear / 45% front axle split when empty
- With a rear conversion (garage, bed, kitchen at back), the rear axle can reach 65–70%
- If the rear axle is over its limit, the van handles poorly and the rear tyres may fail
How to Check Axle Weights
- Find a public weighbridge (most recycling centres and truck stops have them — £10–15)
- Weigh the front axle only (drive the front wheels onto the weighbridge)
- Weigh the whole van (all wheels on)
- Subtract front from total for the rear axle weight
- Compare both to the limits on the VIN plate
Downplating
Downplating is voluntarily reducing the GVW on your V5C. For example, reducing a 3,500kg Sprinter to 3,500kg — wait, that is the same. More commonly, reducing from 3,500kg to 3,500kg... The point is:
Why downplate:
- To reduce road tax (VED): Vans 3,500kg+ pay higher tax
- To fit a lower licence category: Pre-1997 licence holders can drive up to 3,500kg
- To reduce MOT costs: Class 4 vs Class 7
Common downplates:
- 3,500kg → 3,500kg does not make sense
- What people actually do: Buy a 3,500kg van and operate it at whatever weight it actually is. Some vans are originally plated at 3,500kg or 4,250kg and downplated to 3,500kg to fit the standard driving licence.
When you should NOT downplate:
- If your actual weight exceeds the downplated GVW (you would be driving illegally)
- If you carry heavy loads regularly
- If you tow (the towing capacity may change with the downplate)
Materials Selection for Weight Saving
| Heavy Material | Weight | Light Alternative | Weight Saved |
|---|---|---|---|
| 18mm birch ply | 12kg/m² | 9mm ply + rib frame | 6kg/m² |
| MDF worktop | 20kg/m² | Birch ply or bamboo | 10kg/m² |
| Solid timber framing | Heavy | Aluminium extrusion (Bosch Rexroth) | 40–60% |
| Marine ply (12mm) | 9kg/m² | Okoume ply or foam core | 4kg/m² |
| Stone / tile finish | Very heavy | Vinyl floor or thin lino | Negligible |
| AGM battery (100Ah) | 26kg | LiFePO4 (100Ah) | 14kg |
| Full water tank (60L) | 60kg | Carry 20L, fill as needed | 40kg |
| Full gas bottle (6kg) | 12kg | Refillable LPG (lighter cylinder) | 3–5kg |
The single biggest weight saving: Use LiFePO4 batteries instead of AGM. Saving 15–25kg is significant, and you get more usable capacity.
Weighing Your Van
You must weigh your van at least once. It is the only way to know if you are within limits.
| Where | Cost | Accuracy |
|---|---|---|
| Public weighbridge | £10–15 | ±20kg |
| DVSA checkpoint (enforcement) | Free | ±20kg (but you get a fine if over) |
| Scrapyard weighbridge | £5–10 | ±50kg |
| Truck stop | £8–12 | ±20kg |
When to weigh:
- After the bare conversion (before adding gear) — baseline weight
- After fitting all gear — final weight
- Annually — weight creeps up as you add things
Legal Consequences of Being Overweight
| Scenario | Penalty |
|---|---|
| Exceeding GVW by 5–10% | £100–300 fixed penalty |
| Exceeding GVW by 10–20% | £300–500 + possible prohibition notice |
| Exceeding GVW by 20%+ | Court appearance, fine up to £5,000 |
| Exceeding axle weight | Same penalties as GVW |
| Causing an accident while overweight | Insurance voided, potentially dangerous driving charge |
Insurance: If you are overweight and have an accident, your insurance is almost certainly void. Most policies state "the vehicle must be loaded within the manufacturer's specifications." Exceeding GVW breaches this.
FAQ
Q: How much does a campervan conversion weigh? A: A full DIY conversion (insulation, lining, bed, kitchen, electrics, water) weighs 300–500kg. A professional build with bathroom and heavy materials can reach 600–800kg.
Q: How do I weigh my campervan at home? A: You cannot reliably. The best option is a public weighbridge. If you must estimate, use a set of bathroom scales under each wheel (one wheel at a time) and add up the readings. This is inaccurate (±50kg) but gives a rough idea.
Q: Is my Transit Custom overloaded with a full conversion? A: Most Transit Custom 310 builds have 200–400kg of payload remaining after a full conversion, two people, and gear. This is fine. The 290 variant has less margin.
Q: What happens if I get stopped at a DVSA checkpoint? A: They will weigh your van. If overweight, they issue a prohibition notice (you cannot drive further until weight is reduced). They may also fine you. Your van will be inspected for other defects.
Q: Does water count towards payload? A: Yes. Water weighs 1kg per litre. A full 30L fresh tank + 20L grey tank = 50kg. That is significant.
Q: Can I increase my van's GVW? A: Rarely. Some vans have a higher GVW variant (e.g., Transit 340 instead of 310) but upgrading requires suspension modifications, DVLA approval, and often IVA inspection. It is usually easier to reduce weight.
