Loading...
Loading...
Loading calculator...
Calculate how much concrete you need for slabs, footings, columns, and more. Get bag counts and pre-mixed delivery estimates with built-in waste factors.
For projects over 1 cubic yard, ordering pre-mixed concrete delivery is typically more cost-effective and ensures consistent quality.
This calculator provides estimates for planning purposes. Actual concrete requirements may vary based on surface conditions, forms, and waste. Always order 5-10% extra material.
Consult with a concrete supplier for large projects. Factors like reinforcement, finishing, and local building codes may affect your requirements.
Calculating concrete requirements is essential for any construction project. Whether you're pouring a patio, setting fence posts, or building a foundation, knowing exactly how much concrete you need prevents costly over-ordering or project-delaying shortages. Concrete is measured in cubic yards (in the US) or cubic meters (metric), and our calculator converts your dimensions into the exact volume needed, including a waste factor for spills, uneven ground, and over-pours.
Volume = Length × Width × ThicknessFor patios, driveways, sidewalks, and floor slabs. Convert thickness from inches to feet before calculating.
Volume = π × (Diameter/2)² × HeightFor round columns, fence posts, and sonotubes. Multiply by quantity for multiple columns.
Volume = Length × Width × DepthFor foundation footings and retaining walls. All measurements in the same units.
Yields approximately 0.30 cubic feet. Best for small repairs and post holes. Easier to handle but requires more bags.
Yields approximately 0.45 cubic feet. Good balance between weight and coverage. Popular for medium projects.
Yields approximately 0.60 cubic feet. Most economical per cubic foot. Best for larger DIY projects.
Ready-mix concrete delivered by truck. Sold by the cubic yard. Most efficient for projects over 1 cubic yard.
The number of bags depends on your project volume and bag size. An 80 lb bag yields about 0.60 cubic feet. For a 4-inch thick, 10×10 ft slab (33.33 cu ft), you'd need approximately 56 bags of 80 lb concrete. Our calculator does this math automatically and shows options for 40, 60, and 80 lb bags.
One cubic yard equals 27 cubic feet and covers approximately 80 square feet at 4 inches thick, or 65 square feet at 5 inches thick. This is enough for a typical 8×10 ft patio. Most concrete trucks deliver in full or partial yard increments.
Standard thickness depends on use: 4 inches for patios and walkways, 5-6 inches for driveways, and 6-8 inches for heavy vehicle traffic. Always check local building codes, as minimum thickness requirements vary by region and application.
Yes, always add 5-10% for waste. Our calculator includes an adjustable waste factor (default 10%). Waste accounts for uneven ground, spillage, over-pours, and concrete left in the mixer. For complex shapes or rough terrain, consider adding up to 15%.
For projects under 0.5 cubic yards, bags are usually more practical. For 0.5-1 cubic yard, either option works depending on access and timeline. For over 1 cubic yard, ready-mix delivery is more economical and ensures consistent quality. Ready-mix also saves significant labor time.
Concrete reaches about 70% strength in 7 days and full strength in 28 days. You can walk on it after 24-48 hours and drive on it after 7 days. Keep it moist during the first week by spraying with water or covering with plastic to prevent cracking.
For most DIY projects like patios and walkways, wire mesh or fiber reinforcement is sufficient. Driveways benefit from wire mesh or rebar. Structural applications like foundations require rebar per engineering specifications. Reinforcement helps prevent cracking from ground movement and temperature changes.
Standard concrete mix is 3,000-4,000 PSI, suitable for most residential projects including patios, walkways, and footings. Use 4,000-5,000 PSI for driveways and areas with vehicle traffic. High-strength applications may require 5,000+ PSI. Bagged mixes typically come in 3,500-5,000 PSI options.