Marine Battery Cable Size Chart

Marine batteries are the heart of your boat’s electrical system, providing the power necessary to run everything from lights to electronics. But choosing the right size marine battery cable can be a daunting task, and using the wrong size can lead to problems down the line. In this article, we’ll explain how to choose the right size marine battery cable and provide a useful chart to help you find what you need.

Marine Battery Cable Size Chart

Below is a chart that shows the appropriate cable size for a given amperage and cable length. Keep in mind that these are general guidelines, and you may need to consult with an expert or use a calculator for your specific situation.

Gauge American Wire Gauge (AWG) Diameter (mm) Resistance (Ohms/m) Max Amps (A)
1/0 0000 11.7 0.259 135
2/0 000 10.4 0.33 115
3/0 00 9.3 0.415 95
4/0 0 8.3 0.524 80
1 1 7.4 0.654 65
2 2 6.6 0.824 50
3 3 5.8 1.03 40
4 4 5.1 1.3 30
5 5 4.6 1.63 25
6 6 4.1 2.05 20
8 8 3.3 3.21 15
10 10 2.5 5.15 10
12 12 2.0 8.17 8
14 14 1.6 12.9 6
16 16 1.3 20.2 4

What size is marine battery cable?

Marine battery cable comes in a range of sizes, typically from 8 gauge to 4/0 gauge. The gauge refers to the diameter of the wire itself, with smaller numbers indicating larger wires. For most boats, 8 gauge is suitable for up to 45 amps, while 4/0 gauge is necessary for systems up to 600 amps or more.

How do I choose battery cable size?

To choose the right size marine battery cable, you’ll need to consider a few factors. First, determine the total amperage of your electrical system. This includes everything from lights to electronics to winches. To do this, add up the wattage of each device, then divide by the voltage (typically 12 volts for boats).

Once you have your total amperage, use a chart or calculator to determine the appropriate cable size. Keep in mind that longer cable runs require larger cables to avoid voltage drop. It’s also important to consider the environment your cables will be operating in. Saltwater environments can corrode wires more quickly, so you may need to choose cables with better resistance.

What size wire should I use to wire my boat?

In general, 8 gauge wire is suitable for wiring most boats. However, larger boats or those with more electrical systems may require larger cables. It’s important to consult a chart or calculator to determine the right size wire for your particular situation.

What size cable do I need to connect 12V batteries?

To connect 12V batteries, 8 gauge cable is typically sufficient. However, if the batteries are far apart, or you have a large bank of batteries, you may need to use a larger cable to prevent voltage drop.


Choosing the right size marine battery cable is crucial for maintaining a reliable and safe electrical system on your boat. By calculating your total amperage and considering cable length and environment, you can use the marine battery cable size chart to find the appropriate cable size for your needs. And with the right cables in place, you can enjoy your time on the water with confidence.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.