



 
Hi Jeremy, I drew a diagram of the top of the foundation (not to scale) and converted the dimensions to inches. I would first calculate the amount of gravel you need. The gravel fills a space that is 424 inches by 228 inches by 4 feet. You can use our volume calculator to calculate the volume in cubic yards. To find the volume of concrete you need I would use the volume calculator again calculate the volume of the entire region (38 feet by 30 feet by 4 feet) in cubic yards and then subtract the volume of the gravel used. Write back if you need more assistance,
 


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