I am going to be doing a DIY grounding kit with 1/0 gauge wire, but my question is: How much cable will I need?

I know that this topic has been discussed before, but I don't recall reading how much 1/0 cable is needed for the grounding kit.

 

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Someone mentioned oh about 20' the wire is only like 50 cents a ft. I think it was the Home Depot mod King. Maybe the prices have changed by now who knows.