How many 80 lb bags of concrete are in a cubic yard?

A cubic yard is 27 cubic feet. An 80 lb bag of concrete mix yields about 0.6 cubic feet, so a cubic yard is roughly 45 bags. Bag yields vary by product, so check the bag for the exact number.

How many bags do I need for a 10x10 slab?

A 10 x 10 ft slab that is 4 inches thick is about 33.3 cubic feet, or 1.23 cubic yards. At 0.6 cubic feet per 80 lb bag, that is about 56 bags, before any waste allowance. For a pour this size, ready-mix delivery is usually easier.

What thickness should a concrete slab be?

Thickness depends on what the slab will support and on local requirements. Many residential walkways and patios are poured around 4 inches, while driveways are often thicker. Confirm the right thickness for your project before ordering.

Does this calculator include rebar or mesh?

No. Reinforcement is specified separately and depends on the slab's use, soil, and local requirements. The calculator estimates concrete volume only.

Concrete Calculator

Enter the dimensions of a slab, footing, or round pour to estimate the volume in cubic yards, plus the number of 60 lb or 80 lb bags if you plan to mix your own.

Concrete needed

1.36 cubic yards

Including waste, or 37 cubic feet.

Volume: 33.33 cu ft
With waste: 36.67 cu ft
60 lb bags: 82 bags
80 lb bags: 62 bags

Planning note

Bag yields are approximate and based on common 60 lb and 80 lb mixes. For large pours, ready-mix delivery is usually more practical than mixing dozens of bags by hand. Always place and cure concrete according to the manufacturer's instructions.

How this calculator works

The calculator finds the volume of the pour in cubic feet, adds a waste allowance, and divides by 27 to convert to cubic yards. Bag counts use the standard yields for common 60 lb and 80 lb mixes.

slab volume   = length × width × (thickness in ÷ 12)
round volume  = π × (diameter ÷ 2)² × (thickness in ÷ 12)
cubic yards   = volume with waste ÷ 27
bags          = round up (volume with waste ÷ bag yield)

Assumptions

Bag yields assume 0.6 cubic feet for an 80 lb bag and 0.45 cubic feet for a 60 lb bag. Check your product for exact values.
The waste allowance defaults to 10% and can be set to zero for a bare volume.
The calculator does not include reinforcement, forms, base material, or finishing.

Worked example

A 10 ft by 10 ft slab that is 4 inches thick has a volume of 100 × (4 ÷ 12) = 33.3 cubic feet. Dividing by 27 gives 1.23 cubic yards. At 0.6 cubic feet per 80 lb bag, that is about 56 bags.

When to call a professional

Large pours, structural footings, and any concrete work tied to a foundation should be planned and inspected by a qualified professional. Concrete is difficult to redo once it sets, so it is worth confirming the design and thickness before you order.

Frequently asked questions

How many 80 lb bags of concrete are in a cubic yard?: A cubic yard is 27 cubic feet. An 80 lb bag of concrete mix yields about 0.6 cubic feet, so a cubic yard is roughly 45 bags. Bag yields vary by product, so check the bag for the exact number.
How many bags do I need for a 10x10 slab?: A 10 x 10 ft slab that is 4 inches thick is about 33.3 cubic feet, or 1.23 cubic yards. At 0.6 cubic feet per 80 lb bag, that is about 56 bags, before any waste allowance. For a pour this size, ready-mix delivery is usually easier.
What thickness should a concrete slab be?: Thickness depends on what the slab will support and on local requirements. Many residential walkways and patios are poured around 4 inches, while driveways are often thicker. Confirm the right thickness for your project before ordering.
Does this calculator include rebar or mesh?: No. Reinforcement is specified separately and depends on the slab's use, soil, and local requirements. The calculator estimates concrete volume only.

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Last updated: September 25, 2026