Van conversion calculators
The maths a conversion actually needs — worked from published standards and real build data. Free, no account, no email.
Wire gauge & fuse
DC cable gauge and fuse size for a camper van circuit from amps, run length and voltage drop. ABYC ampacity plus the 3 % drop rule, in AWG and mm².
Ventilation (EN 721)
How much fixed ventilation a camper needs under EN 721: high and low vent free area in mm² from your floor area, including the ×2 penalty for wall vents.
Water autonomy
How many days your fresh tank lasts, and what size tank you need. Real off-grid usage figures per person, plus the grey-tank check most planners forget.
Gas locker & vent
Size a camper gas locker and its drop-out vent to EN 1949: internal box dimensions from your bottles, the required floor vent area, and full bottle weights.
Payload & licence
What payload your conversion must leave free: the EN 1646-2 reserve, what is left after kerb and build weight, and whether you stay on a category B licence.
Bed height & garage
Find a bed platform height that clears the bikes underneath and still lets you sit up in bed — the most-regretted dimension in a conversion, worked both ways.
Build order
Tick what your build includes — insulation, windows, solar, electrics, water, gas, heater, shower, bed — and get the phased order and its no-going-back steps.
Insulation quantity
How much insulation a camper van needs: m² per surface from real van dimensions, boards to buy with waste, weight, cost and R-value for XPS, PIR and wool.
Heat loss & heater size
Size a diesel or gas heater for a camper van: heat loss in watts and BTU/hr from real dimensions, insulation, glazing and ventilation — plus fuel per night.
Electrical system sizer
Size a camper van electrical system from your appliances: Wh/day summer and winter, battery Ah by chemistry, solar watts for your latitude, inverter and MPPT.
Or let your layout do the typing
Every calculator here also lives inside the VanPlot editor, where it reads your real van: surface areas, cable run lengths, tank volumes and the parts you've placed. No measuring, no re-typing.
Open the 3D planner — free
Who makes this
I'm Vladimir. I'm planning my own conversion, and none of the tools I tried could tell me whether a layout would fit or what it would do to the rear axle, so I made this one. I work on it alone. If something's wrong or missing, write to me — the address goes to my inbox.
Vladimir Šterjoski