Concrete Calculator
Calculate the exact amount of concrete needed for slabs, footings, columns, walls, and tubes with bag and cost estimates
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Calculate Exactly How Much Concrete You Need
Planning a concrete project? Our concrete calculator helps you determine the precise amount of concrete needed for any shape—slabs, footings, columns, walls, or tubes. Get accurate volume estimates in cubic yards or meters, know how many bags you'll need, and see cost projections before you start.
How Concrete Calculations Work
Concrete is measured in cubic yards (US) or cubic meters (metric). The volume depends on the shape of your project. For slabs and footings, it's length × width × depth. For columns and tubes, we use π × radius² × height. Our calculator accounts for waste (typically 10%) and recommends whether to use bags or order ready-mix based on project size.
Volume Calculation Formula
V = L × W × D (slab) or V = π × r² × h (column)How to Calculate Concrete Needed
Select your project shape (slab, footing, column, wall, or tube)
Enter your dimensions in feet/inches or meters
Adjust the waste factor if needed (10% recommended)
View the calculated volume and bag requirements
See cost estimates for different purchasing options
Common Use Cases
DIY Patios & Sidewalks
Calculate concrete for backyard patios, walkways, and garden paths.
Fence Post Footings
Determine concrete needed for post holes and fence foundations.
Foundation Work
Estimate concrete for footings, stem walls, and small foundations.
Contractor Estimates
Create accurate material quotes for concrete work and avoid over-ordering.
Why Use Our Concrete Calculator?
Any-Shape Volume
Accurate volume calculations for any project shape
Exact Bag Count
Know exactly how many bags of concrete to buy
Built-In Waste Factor
Built-in waste factor prevents shortages
Bags vs Ready-Mix
Cost estimates for bags vs ready-mix delivery
Imperial & Metric
Works in both imperial (feet/yards) and metric units
Frequently Asked Questions
It depends on the bag size: 80 lb bags yield about 0.6 cubic feet, 60 lb bags about 0.45 cubic feet, and 40 lb bags about 0.3 cubic feet. Our calculator shows all three options. For projects over 1 cubic yard, consider ready-mix delivery.
For projects under 1/2 cubic yard, bags are practical. For 1/2 to 1 cubic yard, it depends on your preference. Over 1 cubic yard, ready-mix is usually more economical and efficient, with better quality control.
Standard sidewalks and patios: 4 inches. Driveways: 4-6 inches. Garage floors: 4 inches minimum, 6 inches for heavy vehicles. Footings: typically 8-12 inches, check local building codes.
10% extra accounts for spillage, uneven ground, form imperfections, and leftover concrete in the mixer. It's better to have slightly more than to run short mid-pour, as cold joints weaken the concrete.
80 lb bags cost $5-8 each (about $100-130 per cubic yard). Ready-mix delivery ranges from $125-175 per cubic yard with typical minimum orders of 1-2 yards. There's usually a short load fee for less than full trucks.