How do I tell the amount of amps my 2 amplifiers draw? Want to make sure I obtain the proper fuse size

Using an amprobe on the battery cable is the 100% most accurate way.

Or take all the watt ratings and divide by 13 volts (actual working volts)

ex:

watts divided by voltage = amps
1500/13=115.3


Here is an online converter that will do the math for you.

http://www.jobsite-generators.com/power_calculators.html

To help with fuse size:
http://www.caraudiohelp.com/newsletter/fuse_size.htm

-Brad

Thanks

That would assume a 100% efficiency. I think it would be safer to calculate based on an 80% efficiency. Also if you calculate the need of 40 amps and choose a 50 amp fuse for a little wiggle room make sure you are wiring based on the fuse size of 50 amps. Here is a link to a good wire size calculator Blue Sea Wire Size Calcualtor (http://beta.circuitwizard.bluesea.com/)

All you need to do is make sure its small enough that it won't burn up the wiring. That the point of a fuse so the amp draw doesn't matter as long as you have big enough wire.