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🏗️ Construction Tools

Free Concrete Calculator
— Slabs, Walls & Columns

Instantly calculate concrete volume in cubic yards, feet & metres. Supports slabs, footings, round columns and walls. No sign-up required.

🧮 Calculator

Enter Dimensions

Select shape

Please enter a valid length.
Please enter a valid width.
Please enter a valid depth.
Please enter a valid length.
Please enter a valid height.
Please enter a valid thickness.
Please enter a valid diameter.
Please enter a valid height.
📊 Results

Concrete Required

Fill in the dimensions above and click Calculate.
Total Volume
—
cubic yards
Cubic Feet
—ft³
Cubic Metres
—m³
60-lb Bags
—bags
80-lb Bags
—bags
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📖 How To Use

Calculate Concrete in 4 Steps

No engineering experience needed — just your measurements.

1

Choose your unit system

Select Imperial (feet & inches) or Metric (metres & centimetres). All conversions happen automatically.

2

Select your shape

Pick from slab, wall, round column, footing, curb & gutter, or sonotube. The correct input fields appear automatically.

3

Enter your dimensions

Type in the length, width, and depth (or diameter and height). Add a waste percentage — 5–10% is typical for most jobs.

4

Get instant results

The calculator shows cubic yards, cubic feet, cubic metres, and the number of 60-lb and 80-lb pre-mix bags required.

Concrete Calculator — Complete Guide

What Is a Concrete Calculator?

A concrete calculator is a tool that converts your project's dimensions into the exact volume of concrete you need. Whether you are pouring a driveway slab, setting deck footings, building a retaining wall, or casting round columns, this calculator tells you exactly how many cubic yards or bags to order — saving you money and preventing costly over-ordering.

Concrete is sold by the cubic yard for ready-mix trucks and by the bag for small DIY projects. Our calculator converts both ways, so whether you are calling a concrete supplier or heading to your local home improvement store, you will know exactly what to ask for. Planning a larger build? Also check our Brick Calculator and Fence Calculator to budget your entire project.

The Concrete Volume Formula

The fundamental formula for concrete is straightforward:

Volume (ft³) = Length (ft) × Width (ft) × Depth (ft) Volume (yd³) = Volume (ft³) ÷ 27 Volume (m³) = Volume (ft³) × 0.0283168 Round Column: Volume (ft³) = π × (Diameter/2)² × Height With waste allowance: Final Volume = Base Volume × (1 + Waste% / 100)

Worked Example — Concrete Driveway Slab

Suppose you are pouring a driveway 20 ft long × 10 ft wide × 4 inches thick with a 5% waste allowance:

  • Convert depth: 4 in ÷ 12 = 0.333 ft
  • Base volume: 20 × 10 × 0.333 = 66.67 ft³
  • In cubic yards: 66.67 ÷ 27 = 2.47 yd³
  • With 5% waste: 2.47 × 1.05 = 2.59 yd³ (round up to 2.75 yd³)
  • In 80-lb bags: 2.59 yd³ × 27 × 12 ÷ 3.6 ≈ 234 bags

For this job, ordering a half-yard ready-mix truck is far more economical than bagged concrete. Our Asphalt Calculator can help you cost-compare driveway materials.

How Much Does Concrete Cost?

Ready-mix concrete typically costs $125–$200 per cubic yard (US, 2025), depending on your location, mix strength (PSI), and additives like fiber reinforcement or air-entrainment. Delivery charges add $60–$90 per load. Pre-mixed bags cost roughly $5–$7 for an 80-lb bag, which yields about 0.60 cubic feet. For large pours, ready-mix is almost always cheaper per cubic foot.

Benefits of Planning Your Pour

  • Avoid expensive short-loads (minimum truck delivery charges)
  • Prevent weak spots caused by under-pouring or cold joints
  • Reduce waste and environmental impact
  • Get accurate quotes from concrete suppliers on the first call
  • Properly estimate rebar, mesh, and formwork materials

Pro Tips for Concrete Projects

  • Always add at least 5% for waste, spillage, and uneven sub-base
  • Order in quarter-yard increments — most suppliers round up
  • Check local building codes for minimum slab thickness (typically 4 in for driveways, 6 in for heavy vehicles)
  • Use 3,500–4,000 PSI concrete for driveways and structural footings
  • For stairs or complex shapes, also try our Stair Calculator
  • Ordering gravel sub-base? Use our Gravel Calculator

Planning a garden or outdoor landscaping project alongside your concrete work? Try our Grow a Garden Calculator for planting layouts, or use the Mulch Calculator to cover surrounding garden beds.

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❓ FAQ

Concrete Calculator — Frequently Asked Questions

Divide cubic feet by 27. For example, 54 cubic feet ÷ 27 = 2 cubic yards. Our calculator does this automatically, so you never have to worry about the math.
A 10 ft × 10 ft × 4 in slab requires approximately 1.23 cubic yards or 33.3 cubic feet. You would need about 75 bags of 80-lb concrete or 100 bags of 60-lb concrete, plus a 5–10% waste allowance.
For residential driveways, the standard thickness is 4 inches (10 cm). For driveways supporting heavy vehicles like RVs or trucks, use 5–6 inches. Always check your local building code requirements.
Yes — always add 5–10% for waste. Concrete can be lost to spillage, sub-base unevenness, and formwork imperfections. Running short mid-pour creates cold joints that weaken the structure and are very difficult to fix.
It takes approximately 45 bags of 80-lb Quikrete or similar to make 1 cubic yard of concrete. Each 80-lb bag yields about 0.60 cubic feet; since 1 cubic yard = 27 cubic feet, 27 ÷ 0.60 ≈ 45 bags.
Yes. Select the "Round Column" shape, enter the diameter in inches and the height in feet. The calculator uses the formula π × r² × h to compute the volume. You can also enter the number of columns to get a combined total.
For driveways, use 3,500–4,000 PSI concrete. For footings and structural elements, 4,000 PSI is recommended. For basic sidewalks and patios, 3,000 PSI is sufficient. Always confirm with your local building authority.
Yes, but always round up to the nearest quarter or half yard when ordering from a ready-mix supplier. Most suppliers charge a premium for loads under 3–4 yards (short-load fee), so check minimum order requirements before calling.

Use this Concrete Calculator to quickly estimate the amount of concrete required for construction projects. Whether you’re pouring a slab, footing, column, driveway, or foundation, this tool helps calculate concrete volume accurately. It is useful for homeowners, contractors, builders, engineers, and DIY enthusiasts planning projects of any size.