AWG to mm² Conversion Chart

18 AWG (0.75 mm²) is the thinnest standard cable still considered "wiring" in DC systems — below it, you are into signal-wire and pre-tinned BMS-cable territory. It handles small loads under 7 A: indicator LEDs, low-power dome lights, sensor feeds, and the trigger sides of relays. In stocked metric markets, 0.75 mm² is the smallest cable typically sold off the spool, available alongside 1.0 mm² and 1.5 mm². Anything below 0.75 mm² is usually multi-conductor sheathed cable for trailer plugs or sensor harnesses.

12 AWG (4 mm²) is the workhorse of 15–25 A DC circuits. It is the gauge most camper builders pick for the water pump, vent fan, and USB charger branches — heavier than the 14 AWG lighting circuit, lighter than the 10 AWG fridge feed. In 12V automotive applications it is the standard for accessory sockets, electric awnings, dual-purpose Maxxair fans, and small inverter feeds up to roughly 300 W. The metric pair is 4 mm², stocked in every auto-electrical shop in Europe.

10 AWG is the workhorse of medium-current DC wiring. It handles the loads that are too heavy for general lighting (14 AWG / 12 AWG) but lighter than direct battery interconnects (8 AWG and above). In a typical camper or boat, 10 AWG runs from the fuse panel to the compressor fridge, the heater fan, and from the MPPT solar charge controller to the battery on systems up to roughly 30 amps.

14 AWG is the gauge most camper electricians default to for branch circuits in the 5–15 A range. It handles interior LED lighting, USB outlets, small fans, and 12V cigarette sockets without breaking a sweat. Below 14 AWG you are into signal-wire territory (16 / 18 AWG); above it (12 AWG) is for water pumps, vent fans, and small motor loads. In standard metric cable, 14 AWG corresponds to 1.5 mm² — the most stocked size in European auto-electrical and marine shops.

4 AWG is where DC wiring stops being light branch circuits and starts being serious power transmission. It is the default for battery bank interconnects, feeds to medium inverters (1000–1500 W class at 12V), and the main distribution between battery and fuse panel. At this gauge, friction-fit terminals stop being acceptable — every 4 AWG termination needs a hexagonal crimp die, heat-shrink, and ideally a torque-checked stud connection.

2.5 mm² is the single most stocked cable size in European auto-electrical and marine shops — the default for every branch circuit that outgrows 1.5 mm². Its AWG twin is the oddball: 13 AWG (2.62 mm²) sits between the common even sizes 14 and 12 AWG and is rarely sold in North America. That is why 2.5 mm² datasheets list "13 AWG equivalent" while US shopping lists round to 12 AWG for the same job. At 20 A ampacity, 2.5 mm² covers combined lighting trunks, fridge branches, and heavy accessory circuits.

8 AWG (10 mm²) is the charging-circuit gauge. It is what most camper builders run between the alternator DC-DC charger and the battery, from 40–50 A MPPT controllers to the bank, and as the feed for a small 500 W inverter. It marks the crossover point in termination technique: ring terminals now need a proper crimper instead of pliers, and blade fuses give way to MIDI bolt-down fuses.

6 AWG (16 mm²) is the bridge between branch wiring and battery cables. It feeds mid-size inverters (up to ~700 W at 12V), 60 A shore-power chargers, and serves as the main battery-to-busbar run in smaller builds. Physically it is the last size that still bends easily around interior corners — one reason many boat builders standardize on it for panel feeds even when 8 AWG would pass the math.

2 AWG (35 mm²) is proper battery cable. This is the gauge for 1200 W inverter feeds at 12V, interconnects on 200–400 Ah lithium banks, and the main run from battery to Class T fuse to busbar. Everything about working with it is different from branch wiring: fine-strand welding-style cable for flexibility, hydraulic crimpers for the lugs, and bolt-down fuses (ANL, Class T, MRBF) — there is no blade-fuse territory here.