Advanced Calculators
Concrete Calculator - Calculate Concrete Volume & Cost
Calculate concrete volume, bags needed, and total cost for your construction project. Supports slabs, footings, columns, stairs, and circular areas.
Use Concrete Calculator - Calculate Concrete Volume & Cost to get instant results without uploads or sign-ups. Everything runs securely in your browser for fast, reliable output.
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About this tool
Our Concrete Calculator is the most comprehensive free tool for estimating concrete needs for any construction project. Whether you're planning a simple driveway slab, building foundation footings, pouring concrete columns, or creating decorative circular patios, this calculator provides accurate estimates of volume, materials, and costs. The tool accounts for different project shapes and automatically calculates the exact amount of concrete you need in multiple units: cubic yards (the standard for ready-mix concrete orders), cubic feet (useful for smaller projects), and number of bags (for DIY projects using pre-mixed concrete).
Unlike basic calculators that only handle rectangular slabs, our tool supports five different project types with specialized calculations for each. The slab calculator is perfect for driveways, patios, and garage floors. The footing calculator helps with foundation work and fence posts. The column calculator handles round or square support pillars. The stairs calculator computes the complex geometry of steps and landings. The circular calculator is ideal for round patios, fire pits, and decorative elements. Each calculation includes a recommended waste factor (typically 5-10%) to ensure you order enough material, accounting for spillage, uneven subgrade, and over-excavation.
The cost estimation feature helps you budget your project accurately by calculating both ready-mix concrete costs (priced per cubic yard) and bagged concrete costs (priced per bag). This comparison helps you decide whether to order a concrete truck or buy bags from a hardware store. For small projects under 1 cubic yard, bags are often more economical. For larger projects, ready-mix delivery is typically cheaper and more convenient. The calculator shows you the break-even point and total project cost for both options, helping you make the most cost-effective choice.
All calculations follow industry-standard formulas used by professional contractors and are verified against building codes and construction guidelines. The tool is completely free, requires no registration, and works entirely in your browser without sending data to any server. Perfect for DIY homeowners, contractors, landscapers, and construction professionals who need quick, accurate concrete estimates.
Usage examples
Driveway Slab
20ft × 12ft × 4 inches thick
Volume: 2.96 cubic yards, 80 cubic feet, ~148 bags (40lb)
Foundation Footing
100ft long × 1.5ft wide × 1ft deep
Volume: 5.56 cubic yards, 150 cubic feet, ~295 bags (40lb)
Support Column
12 inch diameter × 8 feet tall
Volume: 0.28 cubic yards, 7.5 cubic feet, ~15 bags (40lb)
Concrete Stairs
4 steps, 4ft wide, 10in rise, 12in run
Volume: 0.74 cubic yards, 20 cubic feet, ~40 bags (40lb)
Circular Patio
10ft radius × 4 inches thick
Volume: 3.88 cubic yards, 105 cubic feet, ~207 bags (40lb)
How to use
- Select your project type (Slab, Footing, Column, Stairs, or Circular)
- Enter the dimensions in feet and inches (Length, Width, Thickness/Height)
- Choose your bag size (40 lb, 60 lb, or 80 lb bags)
- Enter the price per bag or per cubic yard for cost estimation
- View instant results showing cubic yards, cubic feet, bags needed, and total cost
- See the waste factor calculation (typically 5-10% extra for safety)
Benefits
- Accurate volume calculations for 5 different project types
- Results in cubic yards, cubic feet, and number of bags
- Built-in waste factor (5-10%) for realistic material estimates
- Cost comparison between ready-mix and bagged concrete
- Supports both feet and inches for precise measurements
- Instant calculations as you type - no waiting
- Mobile-friendly interface for on-site estimates
- No registration or personal information required
- Completely free with no hidden costs or ads
- Based on industry-standard construction formulas
- Helps prevent over-ordering or under-ordering concrete
- Includes helpful tips for each project type
FAQs
How many 40 lb bags of concrete are in a cubic yard?
A cubic yard of concrete requires approximately 45 bags of 40-pound concrete mix. For 60 lb bags, you need about 60 bags per cubic yard, and for 80 lb bags, you need approximately 90 bags per cubic yard. These are industry-standard estimates used by contractors.
Should I add extra concrete for waste?
Yes, always add 5-10% extra concrete to account for spillage, uneven subgrade, over-excavation, and waste. Our calculator automatically includes this waste factor in the results. For critical projects or complex shapes, consider adding 10% instead of 5%.
How thick should a concrete slab be?
For residential driveways and patios, 4 inches is standard. Garage floors and light vehicle areas should be 4-6 inches. Heavy vehicle areas or commercial applications require 6-8 inches or more. Always check local building codes for requirements in your area.
Is it cheaper to buy bags or order ready-mix concrete?
For projects under 1 cubic yard (27 cubic feet), bagged concrete from a hardware store is often more economical. For larger projects, ready-mix concrete delivered by truck is typically cheaper per cubic yard and much easier. Our calculator shows costs for both options to help you decide.
What is the standard concrete mix strength?
Most residential concrete uses a 3,000 PSI mix for slabs and 3,500-4,000 PSI for structural elements like footings and columns. The mix typically contains Portland cement, sand, gravel, and water in a 1:2:3:0.5 ratio. Pre-mixed bags are formulated to meet these standards when mixed properly.
How do I calculate concrete for odd shapes?
For irregular shapes, break the area into regular shapes (rectangles, circles, triangles), calculate each section separately, then add them together. Alternatively, use the "closest shape" approximation method. For very complex shapes, consider consulting with a concrete contractor for a professional estimate.
What information do I need to order ready-mix concrete?
You need: (1) Total cubic yards required, (2) PSI strength needed, (3) Slump (workability - usually 4-5 inches), (4) Maximum aggregate size, (5) Any special additives (air entrainment for freeze areas, fiber mesh, etc.), and (6) Pour location accessibility for the truck.
Can I pour concrete in cold or hot weather?
Concrete can be poured in various temperatures with precautions. In cold weather (below 40°F), use warm water, accelerators, and insulated blankets to prevent freezing. In hot weather (above 90°F), pour early morning, use cold water, and cure continuously to prevent rapid drying and cracking. Extreme temperatures require special mix designs.
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