CONCRETE
CONCRETE
yd³ = L·W·D ÷ 27
ft
ft
in
RESULT
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For pours over 1 cubic yard, ready-mix delivery is usually cheaper than bags. Add 10% for spillage and over-dig.
About this calculator
Use this concrete calculator to estimate how much concrete you need for a slab, footing, sidewalk, or patio. Enter the length, width, and thickness of your pour, and the calculator returns cubic yards (for ready-mix delivery) plus the equivalent number of 60-pound or 80-pound concrete bags from Home Depot or Lowe's. A 60lb bag yields about 0.45 ft³; an 80lb bag yields 0.60 ft³.
Common questions
When should I use bags vs ready-mix concrete?
Bags make sense for pours under 0.5 cubic yards (about 30–50 ft² of 4-inch slab). Above that, ready-mix delivery is cheaper, faster, and gives a more uniform pour. Most concrete plants have a 1-yard minimum and a per-yard short-load fee.
How many 80lb bags of concrete in a yard?
About 45 bags of 80lb concrete = 1 cubic yard. For 60lb bags it's 60 bags per yard. That's roughly 3,600–4,000 lbs of concrete per yard depending on mix.
How thick should my concrete slab be?
4 inches is standard for residential patios, walkways, and shed pads. Driveways need 4–6 inches with rebar. Garage floors and heavy equipment areas need 6 inches. Footings depend on local code — typically 8–12 inches.