When building a reliable and safe electrical system for your camper or off-grid setup, choosing the correct cable size is crucial. Cables that are too thin can overheat and even cause fires. Oversized cables, on the other hand, are unnecessarily expensive and harder to work with. Our cable calculator helps you find the perfect balance between safety, efficiency, and cost—in just seconds.

⚡ Watts vs. Amps – what do they actually mean?

Watts (W) measure power. They tell you how much energy a device consumes or delivers. Think of a 1500W kettle or a 60W fridge.

Amps (A) indicate current – how much electricity actually flows through a cable.

➡️ How are they connected?

The formula is: Watts = Volts × Amps
Or reversed: Amps = Watts ÷ Volts

Example:
A 120W fridge on a 12V system uses: 120W ÷ 12V = 10A

🔍 Where can you find this information on your devices?

Look for: “Input Power”, “Max Power” or “Current Draw”.

🧯 Why is the correct cable size so important?

Safety
Undersized cables can get hot, melt their insulation, or cause short circuits. Dangerous and often problematic for insurance claims.

Efficiency
Cables that are too thin lead to voltage drop. This means your device may underperform or receive insufficient power.

Compliance & Warranty
Incorrect cables can violate EU electrical standards. And: miswired devices are often not covered by warranty.

✅ Tips when choosing your cable size:

one-way length (from power source to device)

peak power usage, not the average

heat-resistant cables in engine bays or underfloor sections

fuses – they’re your safety net