Cable Gauge Selection Chart
To determine the approximate current-draw (in amperes) of your amplifier (or amplifiers) divide your total RMS power rating by your total peak power figure. Multiply this figure by the fuse rating of your amp (or the total of the fuse ratings of all your amps). Compare this number to the numbers in the "Amperes" column in the chart below. Cross-reference with the cable length (the distance from your battery to the amp mounting location) to determine which gauge of cable you need.