Short answer One standard fence post hole — 12 inches wide and 2 feet deep — needs about 1.6 cubic feet of concrete: 3 bags of 80 lb mix, or 4 bags of 60 lb mix. A post hole is a cylinder, so its volume is π × radius² × depth: for this hole, π … Read more
Short answer: a 20×20 slab at the standard 4-inch thickness needs 4.94 cubic yards of concrete. With the usual 10% safety margin, order 5.5 yards of ready-mix. At roughly $150 per yard, budget about $815 for the concrete alone. The numbers by thickness Thickness Concrete needed (before safety margin) 4 inches (standard) 4.94 cubic yards … Read more
Short answer: a 10×10 slab poured at the standard 4-inch thickness needs 1.24 cubic yards of concrete. Add the usual 10% safety margin and you should order 1.5 yards of ready-mix — or, if you are mixing it yourself, about 62 bags of 80 lb mix (82 bags of 60 lb). Concrete needed by slab … Read more
