How many bags of concrete in a yard?

Bags per cubic yard by bag size

Standard concrete mix, from the QUIKRETE Concrete Mix data sheet

Bag size	Yield per bag	Bags per cubic yard	Bags per cubic foot
40 lb	0.30 cu ft	90	3.33
50 lb	0.375 cu ft	72	2.67
60 lb	0.45 cu ft	60	2.22
80 lb	0.60 cu ft	45	1.67
90 lb	0.675 cu ft	40	1.48

A cubic yard is 27 cubic feet. Bags per yard = 27 ÷ yield per bag. The 90 lb size is sold in some regions only.

Where the yield figures come from

Each manufacturer tests its mix and publishes the volume one bag produces when mixed with the right amount of water. QUIKRETE’s data sheet for its standard Concrete Mix (product 1101) states that a 40 lb bag “yields approximately 0.30 ft³”, a 60 lb bag 0.45 ft³, an 80 lb bag 0.60 ft³ and a 90 lb bag 0.675 ft³. Sakrete’s standard 80 lb mix is listed by its distributors at the same 0.60 cubic feet.

The word “approximately” matters. Yields exclude spillage, uneven ground and over-watering, so the calculators on this site add a waste allowance on top.

Why weight and volume are different

An 80 lb bag does not make 80 lb of concrete; it makes about 0.60 cubic feet, which weighs roughly 90 lb once the water is in. Dry mix is dense, and the finished concrete is a little less dense than you might expect because of the air and water in it. Always work in volume: cubic feet or cubic yards.

How much area one bag covers

Divide the yield by the thickness in feet to get the square feet one bag covers.

Square feet covered by one bag at common thicknesses

Bag size	2 in thick	4 in thick	6 in thick
40 lb	1.8 sq ft	0.9 sq ft	0.6 sq ft
50 lb	2.25 sq ft	1.125 sq ft	0.75 sq ft
60 lb	2.7 sq ft	1.35 sq ft	0.9 sq ft
80 lb	3.6 sq ft	1.8 sq ft	1.2 sq ft
90 lb	4.05 sq ft	2.025 sq ft	1.35 sq ft

Example: 0.60 cu ft ÷ (4 ÷ 12) ft = 1.8 sq ft for an 80 lb bag at 4 in.

Worked example

A 10 × 10 ft shed slab at 4 in:

1. Volume: 10 × 10 × (4 ÷ 12) = 33.3 cu ft
2. With 10% waste: 36.7 cu ft
3. 80 lb bags: 36.7 ÷ 0.60 = 61.1, so buy 62 bags
4. 60 lb bags: 36.7 ÷ 0.45 = 81.5, so buy 82 bags

Sixty-two bags is 4,960 lb of material to carry and mix. That is a full day for two people with a mixer, and it is close to the point where a short ready-mix load is worth pricing. See bags vs ready-mix.

Other products have other yields

• High-yield mixes such as Sakrete MAXIMIZER use lighter aggregate and yield more per bag; the manufacturer states about 1 cubic foot for an 80 lb bag.
• Fast-setting mixes for post holes have their own yields, and manufacturers often rate them by hole size rather than cubic feet.
• Mortar, stucco and sand mix are not concrete and are rated by coverage, not volume.

Whatever you buy, the yield on the bag or the product’s data sheet is the number to use. The calculator’s values are for standard concrete mix.

Water changes the result

Adding more water than the bag calls for makes the mix easier to pour and slightly larger in volume, but it weakens the concrete and makes it crack and dust. Measure the water, mix to a stiff, workable consistency, and use the yield as printed.