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🧱Concrete Calculator

Calculate Concrete Volume & Materials

Get precise measurements for concrete slabs, footings, and walls. Calculate cubic yards, concrete bags, and project cost with our free concrete calculator.

Project Details

Quick Presets

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ft
in
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Results

Cubic Yards (with Waste)

1.30 cu yd

80lb Bags

59

60lb Bags

78

40lb Bags

117

Estimated Cost

$162.04

💡 Pro Tip

For larger projects, consider ordering 5-10% extra concrete to account for spillage, uneven excavation, or last-minute changes.

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Quick Answer

Concrete estimates usually start with the project area or volume, then add a waste factor before converting the result into bags, pieces, bundles, panels, or gallons. Use this calculator when you need a fast material estimate before ordering supplies, comparing costs, or planning a construction project.

Best for

Contractors, builders, remodelers, and DIY homeowners who need a practical jobsite estimate.

Inputs needed

Start with the dimensions of the project, then choose material settings, price, and waste percentage.

How to estimate

The basic workflow is to measure dimensions, convert units, calculate volume, then round up so you do not run short during installation.

How many 80lb bags of concrete make a yard?

It takes approximately 45 bags of 80lb concrete to make one cubic yard (27 cubic feet). An 80lb bag yields about 0.6 cubic feet.

Concrete Volume Formula

Volume = Length × Width × Thickness

Calculate the volume of concrete needed for your project. Multiply the length, width, and thickness (convert inches to feet first) to get cubic feet, then divide by 27 to get cubic yards.

Step-by-Step Guide

1

Measure Dimensions

Accurately measure the length, width, and thickness of your concrete project in feet and inches.

2

Convert Units

Convert all measurements to the same unit (feet for imperial, meters for metric).

3

Calculate Volume

Multiply length × width × thickness to get total volume.

4

Add Waste Factor

Add 5-10% extra for spillage, uneven surfaces, and mistakes.

5

Convert to Yards

Divide cubic feet by 27 to get cubic yards, or use bag counts for small projects.

Pro Tips

  • Always round up to the next whole number when ordering concrete.
  • For slabs, use concrete with fiber reinforcement for crack resistance.
  • Check local building codes for minimum thickness requirements.
  • Consider the weather - concrete cures faster in hot, dry conditions.
  • Order ready-mix concrete for large projects to ensure consistency.

Frequently Asked Questions

How many 80lb bags of concrete make a yard?
It takes approximately 45 bags of 80lb concrete to make one cubic yard (27 cubic feet). An 80lb bag yields about 0.6 cubic feet.
What is the recommended thickness for a concrete slab?
For a typical patio or walkway, 4 inches is standard. For driveways, use 5-6 inches. For heavy vehicle traffic, consider 6-8 inches.
How long does concrete take to cure?
Concrete reaches about 70% strength in 7 days and full strength in 28 days. Keep it moist for at least 3 days for optimal curing.
What waste factor should I use?
For most projects, 10% waste is recommended. For complex shapes or uneven ground, consider 15% extra.
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