Bag Calculator — How Many Bags of Concrete Do I Need?

Start from a volume, a project size, or the bags already in your garage. All three directions use the manufacturers' published yields: 80 lb = 0.60 cu ft, 60 lb = 0.45, 50 lb = 0.375, 40 lb = 0.30.

How many bags do I need?

Volume needed

Unit 1 cu yd = 27 cu ft. Default above is exactly 1 cu yd.

Waste / overage allowance Always order a little extra. You cannot send back a shortage mid-pour.

Prices — national-average defaults, edit to your local prices

80 lb bag ($)

60 lb bag ($)

50 lb bag ($)

40 lb bag ($)

Ready-mix ($ per cu yd) National average; roughly $140–$170 in most areas.

Delivery fee ($)

Defaults are planning averages, not quotes. Your supplier's prices are the real ones — type them in.

Concrete to order (with your waste allowance)

0 cu yd

80 lb bags

60 lb bags

50 lb bags

40 lb bags

Mix it yourself (bags)

Ready-mix truck

Estimates only. Bag counts are always rounded up — you cannot buy a partial bag, and running one bag short mid-pour is worse than having one left over. Unopened bags keep for months in a dry garage and most stores take them back.

I have bags — how much will they cover?

Number of bags

Bag size

Pour thickness (inches)

Your bags make

0 cu ft

That is 0 cu yd of concrete — enough for a slab of about 0 sq ft at the thickness you picked.

Worked example: 30 bags of 80 lb mix: 30 × 0.60 = 18.0 cu ft = 0.67 cu yd. Poured 4 inches thick, that covers 18 / (4/12) = 54 sq ft — roughly a 6 × 9 ft pad.

The yield chart

Bag size	Yield per bag	Bags per cu yd	Bags per cu ft
80 lb	0.60 cu ft	45	1.7
60 lb	0.45 cu ft	60	2.2
50 lb	0.375 cu ft	72	2.7
40 lb	0.30 cu ft	90	3.3

Frequently asked questions

How many 80 lb bags make a yard?

45 bags. One cubic yard is 27 cu ft, and each 80 lb bag yields 0.60 cu ft: 27 / 0.60 = 45. That is also 3,600 lb of dry mix plus water — which is why a yard is where most people switch to a ready-mix truck.

Are bag yields the same for every brand?

Quikrete and Sakrete rate their standard mixes identically (80 lb = 0.60 cu ft, and so on), and the calculators here use those published numbers. Fast-setting and high-strength mixes follow the same yields. Specialty lightweight mixes differ — check the bag if you are using one.

Why does the calculator round bag counts up twice?

Once because you cannot buy a fraction of a bag, and once for the waste allowance — spillage, mixer residue, and uneven forms are real. The panel always shows the exact count too, so you can see both numbers and decide for yourself.