Bags per Cubic Yard: The Exact Math
The answer is 45. Here is why, and what it implies for your project.
One cubic yard is 27 cubic feet and an 80 lb bag yields 0.6 cubic feet, so 27 / 0.6 = 45 bags per yard. Sixty-pound bags: 60 per yard. Forty-pound bags: 90 per yard. That is 3,600 pounds of bags per yard, which is why trucks exist.
The derivation
A cubic yard is 3 x 3 x 3 feet = 27 cubic feet. An 80 lb bag of premix yields about 0.6 cubic feet of cured concrete (the dry ingredients compact and the water adds little volume). 27 divided by 0.6 = 45 bags exactly. For 60 lb bags: 27 / 0.45 = 60 bags. For 40 lb bags: 27 / 0.3 = 90 bags.
Why it surprises people
Forty-five bags sounds like a lot until you do the weight: 45 x 80 = 3,600 pounds per yard, nearly two tons you would otherwise mix by hand. A 2-yard patio is 90 bags and 7,200 pounds. The number is the best argument for the ready-mix breakpoint at 1 to 2 yards.
Does mix type change the count
Barely. High-strength, fast-setting, and crack-resistant premixes all yield within a few percent of 0.6 cubic feet per 80 lb bag, because the chemistry changes strength, not volume. Specialty lightweight mixes are the exception and print their yield on the bag.
From bags to truck loads
Standard mixer trucks carry 8 to 10 yards. Your 2-yard patio is a quarter truck, which is why suppliers charge short-load fees below their minimum, often 1 to 4 yards depending on the plant. Ask about the minimum before you assume the truck is automatically cheaper.
Skip the arithmetic
Convert your project to yards and bags in one step with the calculator.
Bags-per-yard questions
How many 80 lb bags in a cubic yard?
45. A cubic yard is 27 cubic feet and an 80 lb bag yields about 0.6 cubic feet, so 27 / 0.6 = 45 bags.
How many 60 lb bags in a yard?
60. A 60 lb bag yields about 0.45 cubic feet, so 27 / 0.45 = 60 bags per cubic yard.
How many 40 lb bags in a yard?
90. A 40 lb bag yields about 0.3 cubic feet, so 27 / 0.3 = 90 bags per cubic yard.
How much does a yard of bagged concrete weigh?
About 3,600 pounds: 45 eighty-pound bags. Add roughly 5 gallons of water per bag at mixing time on top of that.