How this is calculated
Concrete volume depends on three dimensions: Volume = Length × Width × Thickness. We convert thickness from inches to feet, calculate cubic feet, then convert to cubic yards (÷27) and round up to the nearest quarter yard so your order matches how ready-mix suppliers actually sell concrete. Bags are estimated separately at one 80 lb bag per 0.6 cubic feet for smaller DIY pours where bagged mix makes more sense than a truck delivery.
FAQ
An 80 lb bag yields about 0.6 cubic feet once mixed — roughly 45 bags per cubic yard, or 60 bags of the smaller 60 lb size. For large pours over 1-2 cubic yards, ready-mix delivery is usually cheaper and less labor-intensive than mixing dozens of bags by hand.
Typically 4 inches for patios, walkways, and garden sheds. Driveways, garage floors, and areas with vehicle traffic need 5 to 6 inches, often with reinforcing rebar or wire mesh to prevent cracking under load.
Yes — this calculator already rounds up to the nearest quarter cubic yard to reduce the risk of running short mid-pour, which creates a visible cold joint where old and new concrete meet.
Concrete is typically safe to walk on after 24 to 48 hours, needs about 7 days for light foot traffic and furniture, and a full 28 days to cure completely before parking a vehicle on it.
Common Mistakes to Avoid
Pouring on a hot, windy day with no curing plan — the surface can dry too fast and crack before it cures properly.
Skipping control joints on a larger slab — concrete will crack somewhere eventually; control joints just decide where.
Not compacting the gravel base layer before pouring.
Pro Tips
Keep the surface moist for the first several days (plastic sheeting works well) — a slower cure is a stronger cure.
Order slightly more than the bare minimum — running short mid-pour leaves a visible cold joint where old and new concrete meet.
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