Cubic feet to gallons

I have 5 gallon Root Trapper II containers.
I'm getting ready to order soil ( Coco Loco).
I forgot how much soil (gallons) it takes to fill a container and how to convert to cubic feet.
I'll have 10 Root Trappers total so how many 1.5 cu ft bags?

 

[MickJ]

5 bags

Sent from my comfy chair.
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