Concrete Calculator FAQ

Multiply length × width × thickness in feet, then divide by 27 to get cubic yards. See the formula, a size chart, and how much waste to add.

Length (ft) × width (ft) × thickness (ft) ÷ 27 = cubic yards of concrete. Worked examples for slabs, footings, post holes, and round columns.

A 4-inch slab needs about 1.23 cubic yards per 100 square feet. Use the chart to find the yardage for common slab sizes, or run your own numbers.

Divide your total cubic feet by the bag yield: 0.6 for an 80 lb bag, 0.45 for a 60 lb bag. See the full chart and worked examples for slabs and posts.

It takes 45 bags of 80 lb concrete mix to make one cubic yard, or 60 bags of 60 lb mix. Full chart for 40, 50, 60, 80, and 90 lb bags.

An 80 lb bag of concrete mix yields about 0.6 cubic feet. A 60 lb bag yields 0.45 and a 40 lb bag yields 0.3. See yields for every common bag size.

A 10x10 slab at 4 inches thick needs 56 bags of 80 lb concrete mix, or 75 bags of 60 lb mix. See counts for 4, 5, and 6 inch thicknesses.

Most 4x4 fence posts take 2 to 3 bags of 60 lb concrete per hole, or 2 bags of 80 lb. See the chart by hole diameter and depth, plus the formula for any size.

A pallet of 80 lb concrete mix holds 42 bags, about 3,360 lb and 25.2 cubic feet. See pallet counts and weights for 40, 50, 60, and 80 lb bags.

Ready-mix concrete runs about $140 to $200 per cubic yard delivered in 2026, before short-load fees. See what drives the price and how to budget a small pour.

A cubic yard of concrete is 27 cubic feet, covers 81 square feet at 4 inches, weighs about 4,050 lb, and costs roughly $140 to $200 delivered.

A poured concrete slab costs about $6 to $12 per square foot installed in 2026, averaging around $8. See costs by slab size and what DIY saves.

A standard ready-mix truck holds 8 to 11 cubic yards, and most deliver 9 to 10 because of road weight limits. See capacities and what a full load weighs.

A full 10 yard truck of concrete costs roughly $1,400 to $2,000 delivered in 2026. See the price breakdown, delivery fees, and cost per square foot.

A cubic yard of concrete weighs about 4,050 lb, or roughly 2 tons, at a standard density of 150 lb per cubic foot. See wet vs cured and metric weights.

A cubic foot of normal-weight concrete weighs about 150 lb, or 145 lb without reinforcement. See weights by slab thickness and mix type.

Four inches is standard for patios, walkways, and shed pads. Driveways need 5 to 6 inches, and anything carrying trucks or RVs needs 6 inches or more.