Concrete Bag Calculator
Convert a concrete volume into the number of 40, 50, 60 and 80 lb bags — all four sizes side by side.
What you need
50
80 lb bags — 0.60 cu ft each — the fewest bags, the heaviest lift.
- 60 lb bags
- 66
- 50 lb bags
- 80
- 40 lb bags
- 99
- Volume including waste
- 1.10 cu yd
- Same volume in cubic feet
- 29.7 cu ft
- Total weight to move (80 lb bags)
- 2.00 US tons
0.45 cu ft each.
0.375 cu ft each.
0.30 cu ft each.
Estimates for planning. Confirm quantities with your supplier before ordering — see the assumptions below for the figures used.
How to use the concrete bag calculator
If you already know how much concrete you need, this converts it straight into bag counts for every size on the shelf, so you can compare price and how much lifting you are signing up for. Bag yields are the manufacturer's published figures.
What this calculator assumes
Every estimate depends on figures that vary by supplier and conditions. These are the ones used here, so you can sanity-check the result against your own quote.
- Bag yields are manufacturer figures for standard concrete mix: 0.30 cu ft (40 lb), 0.375 cu ft (50 lb), 0.45 cu ft (60 lb) and 0.60 cu ft (80 lb).
- One cubic yard is 27 cubic feet, which works out to 45 eighty-pound bags or 90 forty-pound bags.
- Fast-setting and high-strength mixes yield slightly differently — check your bag.
Frequently asked questions
How many bags of concrete make a cubic yard?
Forty-five 80 lb bags, 60 sixty-pound bags, 72 fifty-pound bags or 90 forty-pound bags. That is 3,600 pounds of material either way — worth knowing before you load a cart.
How many 80 lb bags of concrete do I need for a fence post?
Around two to three for a typical 4x4 post in a 10 inch hole 2 to 3 feet deep. Many people use one bag per post and end up with a wobbly fence a year later.
Is it cheaper to buy 80 lb or 60 lb bags?
Eighty-pound bags are almost always cheaper per cubic foot, and you handle fewer of them. Sixty-pound bags exist because 80 pounds is a genuinely awkward lift — if you are working alone or carrying any distance, the smaller bag is worth the premium.
How much water does a bag of concrete need?
About 3 quarts for an 80 lb bag, but always work to the bag's instructions and add water gradually. Extra water makes the mix easier to place and measurably weaker — over-watered concrete can lose a third of its strength.
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