Length in feet multiplied by width in feet multiplied by height in feet divided by 27 equals cubic yards needed.
When dealing in inches: convert inches to feet by dividing by 12.
For example: pour a 25 ft. sidewalk 5 ft. wide and four inches deep.
(25’ x 5 ‘ x 0.333’) / 27 = 1.54 cubic yards
Note* we achieved 0.333 ft. by taking four inches and dividing by twelve.
Another example: yardage for an 80 ft. driveway, 24 ft. wide and 5 inches deep.
(80’ x 24’ x 0.416’) / 27 = 29.58 cubic yards