i have a trench to fill with concrete the size is [57 feet long .x 18 inches wide. x 39 inches high.]would like to know how much concrete should i order. thanks.

Hi,

The subject line of your email was "cubic meter" so I am going to calculate the volume in cubic meters. There are 2.54 cm in an inch so

57 ft = 57 12 inches = 57 12 2.54 cm = 1737.36 cm = 17.3736 m
18 inches = 18 2.54 cm = 45.72 cm = 0.4572 m
39 inches = 39 2.54 cm = 99.06 cm = 0.9906 m

Thus you need

17.3736 0.4572 0.9906 = 7.9 cubic meters of concrete.

Penny