Payload and weight, explained

The only sum that matters

Payload = GVW − kerb weight.

GVW (gross vehicle weight) is on the VIN plate and the V5C. Kerb weight varies by options, fuel and how the brochure was written. Treat brochure kerb as optimistic until a weighbridge says otherwise.

What eats the payload

• The conversion itself: often 400 to 700kg depending on how heavy you build
• Water: 1kg per litre. A 100L tank is 100kg when full
• Two adults: around 160kg
• Gear, bikes, tools, dog: 100kg appears before you notice

Add those up against your usable payload after people, water and camping kit. If the maths is uncomfortable early, change the plan while plywood is still cheap.

Habits that keep you legal

1. Weigh the empty van at a weighbridge before you start. It costs about twenty pounds and it is the most useful number you will get.
2. Keep a running weight log as you buy. That is what the tracker on this site is for.
3. Heavy things go low and between the axles.
4. Weigh again fully laden before a long trip.

When you are close to the limit

Overloading is an offence, can invalidate insurance and makes the van drive badly. If you are near the edge, look at lighter materials, less water capacity, or a proper payload uprate with the paperwork done correctly.

Do not guess. Weigh. Then build to the number you measured.

Figures in this guide are planning estimates. Confirm weights and prices against real products, and have gas and electrical habitation work signed off by a qualified person.