Concrete Bag Yield & Coverage Chart

Quick answer: a cubic yard of concrete is 27 cubic feet — that's 45 eighty-pound bags, 60 sixty-pound bags, or 90 forty-pound bags. One cubic yard covers about 81 square feet at 4 inches thick. The tables below are the numbers you actually need to order concrete; for an exact figure on your job, use the concrete slab calculator or the matching concrete calculators.

Bags of concrete per cubic yard

Every bag of dry mix lists a yield — the volume of wet concrete it makes. Divide 27 ft³ by the yield to get bags per cubic yard.

Bag size	Yield (wet)	Bags per cubic yard
40 lb	0.30 ft³	90
60 lb	0.45 ft³	60
80 lb	0.60 ft³	45

Yields are nominal and vary a little by brand and mix, so treat the bag count as a close estimate and buy a spare bag or two.

Concrete coverage by slab thickness

How far a given amount of concrete spreads depends entirely on thickness. These are the two figures people ask for most — area per cubic yard (for ordering ready-mix) and area per 80-lb bag (for small pours).

Slab thickness	Coverage per cubic yard	Coverage per 80-lb bag
2 in	162 sq ft	3.6 sq ft
3 in	108 sq ft	2.4 sq ft
4 in	81 sq ft	1.8 sq ft
5 in	64.8 sq ft	1.44 sq ft
6 in	54 sq ft	1.2 sq ft

Concrete for common slab sizes

All at the standard 4-inch thickness. Cubic yards are exact; bag counts include about 10% waste (you can't pause a pour, and the subgrade is never perfectly flat).

Slab size	Cubic yards	80-lb bags	60-lb bags
4 × 4 ft	0.20	10	14
6 × 6 ft	0.44	22	30
8 × 8 ft	0.79	40	53
10 × 10 ft	1.23	62	82
10 × 12 ft	1.48	74	98
12 × 12 ft	1.78	88	118
12 × 16 ft	2.37	118	157

Notice how fast the bag counts climb: anything past roughly half a cubic yard (about 23 eighty-pound bags) is cheaper and far easier as ready-mix. Use the concrete slab calculator for other sizes and thicknesses.

Round columns & Sonotube fill

A round column, pier, or cardboard tube form (like a Sonotube) holds π × radius² per foot of height. This is the concrete per foot — multiply by your tube height.

Tube diameter	Concrete per foot	80-lb bags per foot
6 in	0.20 ft³	0.3
8 in	0.35 ft³	0.6
10 in	0.55 ft³	0.9
12 in	0.79 ft³	1.3
14 in	1.07 ft³	1.8
16 in	1.40 ft³	2.3
18 in	1.77 ft³	3.0

So a 12-inch tube 4 feet tall needs about 0.79 × 4 = 3.2 ft³, or roughly 6 eighty-pound bags with waste. The concrete column calculator handles any diameter, height, and quantity.

Quick conversions

• 1 cubic yard = 27 cubic feet
• 1 cubic yard of concrete ≈ 4,000 lb (about 2 US tons)
• Bag yields: 80 lb = 0.60 ft³ · 60 lb = 0.45 ft³ · 40 lb = 0.30 ft³
• Switch to ready-mix past about 0.5 cubic yard (≈ 23 eighty-pound bags)

How to use this chart

For a slab, find your thickness in the coverage table and divide your area by the coverage figure. For a footing or wall, work out the volume (length × width × depth, in feet) and divide by 27 for cubic yards or by the bag yield for bags — the concrete footing and concrete wall calculators do it for you. Most slabs and footings also sit on a compacted gravel base; size that with the gravel calculator. Whatever you pour, order about 10% extra.