Concrete Slab & Volume Calculator

Calculate how many cubic yards or premix concrete bags (80 lb or 60 lb) you need for pouring concrete slabs, patios, or driveways.

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Concrete Dimensions

Enter slab dimensions in feet and inches.

Length (ft)

Width (ft)

Thickness (in)

1.23 Cu Yds 56 Bags (80 lb each)

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For pours over 1 cubic yard, ordering ready-mix truck delivery is significantly faster and more economical than hand-mixing bags.

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Cubic Yards = (Length ft × Width ft × (Thickness in / 12)) / 27

Applies standard American Concrete Institute (ACI) volume equations and premix bag yield factors.

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Add a 10% spillage and subbase variance margin when ordering ready-mix concrete.

Follow these simple steps for accurate concrete ordering:

Measure formwork dimensions in feet using a measuring tape.

Enter slab thickness in inches (standard patio/walkway thickness is 4 inches).

Instantly view calculated total cubic yards and 80lb/60lb premix bag counts required.

Calculating exact concrete volume prevents costly short-load delivery fees or having extra hardening concrete.

Input

Outer boundary measurements of the concrete formwork.

Output

Total wet volume required for ordering.

How many 80lb bags of concrete make a cubic yard?

It takes 45 bags of 80 lb concrete premix (or 60 bags of 60 lb premix) to yield 1 cubic yard of mixed concrete.

How thick should a residential concrete driveway be?

Standard passenger car driveways require 4 inches of 4,000 PSI concrete over a compacted gravel subbase (5 to 6 inches for heavy RVs).