Cubic yards and 80 lb bags of concrete for a slab.
AdvertisementA 10x10 ft slab 4 in thick needs about 1.36 cubic yards of concrete, or 62 bags of 80 lb premix.
We multiply length by width by thickness to get the volume, add 10% for spillage and uneven ground, and divide by the yield of one bag: an 80 lb bag of premix makes about 0.6 cu ft. One cubic yard is 27 cu ft.
4 in is standard for patios, walkways and shed floors. Driveways and garage floors usually need 5 to 6 in.
About 45 bags of 80 lb premix make one cubic yard, since each bag yields roughly 0.6 cu ft.
About 2.04 cubic yards with 10% extra, or 92 bags of 80 lb mix. At that size, ready-mix delivery is usually cheaper and much less work than mixing bags.
You can usually walk on it after 24 to 48 hours and drive on it after about 7 days. It reaches its full strength in about 28 days.