



 
Hi Sam, A solid region 4" by 4" by 2" is $4 \times 4 \times 2 = 32$ cubic inches. You know that 32 cubic inches of the glass pebbles weighs 5 pounds so that's $\large \frac{5}{32} \normalsize = 0.156$ pounds per cubic inch. You didn't tell us how deep the fire pit is but using the depth and our volume calculator find the volume of the hole you need to fill, in cubic inches. Multiply he volume by 0.156 to obtain the weight of the glass pebbles required. Penny  


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