Campervan Cable Size Calculator

Calculate cable size, voltage drop and fuse rating for campervan, motorhome and off-grid 12V / 24V / 60V systems.

Circuit type

Interior: low/medium current, continuous.
High current: starter, inverter, winch.
Solar: PV and charge-controller wiring.

System voltage

Load current (A)

If unknown, enter power (W) below – current will be estimated.

Load power (W) – optional

I ≈ P / V. If you enter both A and W, the calculator will use the amps.

Cable length – one way (m)

Measure distance from battery / fusebox to the load only – the calculator will use the full circuit length (out + return).

Allowed voltage drop (%)

Interior: 3–5% • High current: 5–10% • Solar: 3–5%

Recommended Cable & Fuse

Calculated load current:

Minimum required area:

Recommended MKGT cable:

Estimated voltage drop:

Voltage drop (%):

Power loss in cable:

Recommended fuse:

Fuse is calculated at approx 125% of load current and rounded up to a common automotive value.

Calculator assumes copper conductors, typical ambient temperatures and single circuits. Always check product datasheets, installation standards and local regulations.

How to Use the Campervan Cable Size Calculator

This tool is designed for campervan, motorhome, 4x4 and off-grid electrical systems. It helps you choose the correct MKGT cable size, check voltage drop and select a suitable fuse rating for three main circuit types:

Interior 12V/24V loads – lights, pumps, fridges, USB sockets, fans.
High-current circuits – inverters, DC-DC chargers, winches, starter cables.
Solar wiring – panel to MPPT, MPPT to battery.

Step 1 – Select the Circuit Type

Choose whether you are sizing a low-current interior circuit, a high-current battery cable, or a solar/DC run. The calculator automatically suggests a reasonable voltage-drop limit for each scenario.

Step 2 – Enter Voltage, Load and Cable Length

System voltage – 12 V, 24 V or 60 V.
Load current (A) – if you know the current draw.
Load power (W) – if you only know the power; the calculator will estimate current from P / V.
Cable length – one way – distance from battery/fusebox to the load. The calculator uses the full circuit length (out + return).

Step 3 – Check the Recommended Cable

The result shows:

Minimum required cross-section in mm².
Recommended MKGT cable size (2-core flat cable for interior/solar, or MKGT battery cable for high-current use).
Estimated voltage drop in volts and percent.
Power loss in the cable.

Step 4 – Fuse Size Recommendation

The calculator also suggests a fuse rating based on approximately 125% of the calculated load current, rounded up to the nearest common automotive value (e.g. 10 A, 15 A, 20 A, 30 A, 50 A, 100 A, etc.). Always ensure the fuse, cable and connectors are all correctly rated for the installation.

Technical Reference & Additional Tools

For a deeper technical explanation of cable sizing, voltage drop, current ratings and installation examples, you can download the free MKGT technical guides:

MKGT 2-Core Cable Technical Guide (PDF)
Download 2-Core Cable Guide
MKGT Battery Cable Technical Guide (PDF)
Download Battery Cable Guide

These documents include diagrams, example calculations and application tables for 2-core automotive cable and MKGT battery cable up to 95 mm². They are ideal for campervan builders, auto electricians and anyone working with low-voltage DC systems.

Campervan Cable Size Calculator – MKGT Technical Guide for 12V / 24V / 60V Systems