Concrete Bag Yields by Bag Size

Concrete bag yields

An 80 lb bag of concrete mix makes about 0.60 cubic feet of concrete, so a cubic yard takes 45 bags. A 60 lb bag makes 0.45 cu ft (60 bags a yard) and a 40 lb bag 0.30 cu ft (90 bags a yard).

Yield of each bag size

These yields are from the QUIKRETE Concrete Mix (No. 1101) data sheet, which lists every size from 40 to 90 lb. QUIKRETE 5000 gives the same yields for its 50, 60 and 80 lb bags, and Sakrete lists 0.6 cu ft for its 80 lb High-Strength Concrete Mix. All work out to the same 133 lb of dry mix per cubic foot of concrete.

Concrete mix yields
Bag	Yield	Liters	Bags per cu yd	Bags per cu ft	Lb of mix per cu ft
40 lb	0.3 cu ft	8.5 L	90	3.33	133.3
50 lb	0.375 cu ft	10.6 L	72	2.67	133.3
60 lb	0.45 cu ft	12.7 L	60	2.22	133.3
80 lb	0.6 cu ft	17 L	45	1.67	133.3
90 lb	0.675 cu ft	19.1 L	40	1.48	133.3

A yield is approximate: it assumes the right amount of water and full compaction. QUIKRETE gives its mixed Concrete Mix a density of about 140 lb per cubic foot, a little more than the dry weight per cubic foot because of the water added.

Bags for a 4 in slab

Bags with no extra; add 5 to 10% before you buy
Slab	40 lb	50 lb	60 lb	80 lb	90 lb
4 × 4 ft	18	15	12	9	8
4 × 8 ft	36	29	24	18	16
6 × 6 ft	40	32	27	20	18
8 × 8 ft	72	57	48	36	32
10 × 10 ft	112	89	75	56	50
10 × 12 ft	134	107	89	67	60
12 × 12 ft	160	128	107	80	72

Bags for a post hole

Concrete for an empty hole; a post takes some of the space
Hole (diameter × concrete depth)	Cu ft	50 lb bags	60 lb bags	80 lb bags
6 in × 24 in	0.39	1	0.9	0.7
8 in × 24 in	0.7	1.9	1.6	1.2
8 in × 36 in	1.05	2.8	2.3	1.7
10 in × 30 in	1.36	3.6	3	2.3
10 in × 36 in	1.64	4.4	3.6	2.7
12 in × 36 in	2.36	6.3	5.2	3.9
12 in × 48 in	3.14	8.4	7	5.2

For a fence, the fence post calculator subtracts the post and the gravel at the bottom of the hole.

Mixing

QUIKRETE asks for at least 1 cu ft of mixer capacity for each 80 lb bag. Its data sheet starts with about 6 pints (2.8 liters) of water per 80 lb bag and adds more only until the mix is stiff and moldable. Too much water weakens the concrete, and it does not make more of it: the yield stays about the same.

Sources

QUIKRETE Concrete Mix (No. 1101) data sheet, The QUIKRETE Companies, revised October 2022. Bag yields: 40 lb 0.30 cu ft, 50 lb 0.375, 60 lb 0.45, 80 lb 0.60, 90 lb 0.675; about 140 lb per cubic foot.
QUIKRETE 5000 High Early Strength Concrete Mix (No. 1007) data sheet, The QUIKRETE Companies, revised November 2022. Bag yields: 50 lb 0.375 cu ft, 60 lb 0.45, 80 lb 0.60.
Sakrete High-Strength Concrete Mix 80 lb product page, Sakrete (Oldcastle APG), current listing. An 80 lb bag yields 0.6 cu ft, the same as QUIKRETE Concrete Mix.
QUIKRETE Fast Setting Concrete Mix (No. 1004) data sheet, The QUIKRETE Companies, current sheet. A 60 lb bag yields about 0.45 cu ft.