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How Many Bags of Concrete for a 10×10 Slab? (4-Inch & 6-Inch 80lb vs 60lb Chart)

A 10×10 concrete slab requires 1.23 net cubic yards (33.3 cu ft) at a 4-inch depth, requiring 62 bags of 80 lb concrete or 82 bags of 60 lb concrete with a 10% contingency allowance.

Published Trade Methodology · Standard Architectural Takeoff · Calculation Standards

The Engineering Concrete Volume Formula

Calculating the volume of any square or rectangular concrete slab begins with converting all three dimensions (length, width, and depth) into feet, multiplying them to find total cubic feet, and dividing by 27 to calculate cubic yards:

  Cubic Yards Formula:

  Volume (yd³) = [ Length (ft) × Width (ft) × Depth (inches ÷ 12) ] ÷ 27

For a standard 10 × 10 ft slab:

At 4-inch depth (0.333 ft): 10 × 10 × 0.333 = 33.33 cu ft. Dividing by 27 yields 1.23 net cubic yards. Factoring in a mandatory 10% allowance for subbase settling, uneven gravel grading, and spillage, your ordering volume is 1.36 cubic yards (36.8 cu ft).
At 6-inch depth (0.500 ft): 10 × 10 × 0.500 = 50.00 cu ft. Dividing by 27 yields 1.85 net cubic yards. Adding 10% contingency equals 2.04 cubic yards (55.0 cu ft).

Concrete Bag Yields: 80 lb, 60 lb, and 40 lb Mixes

Pre-mixed concrete bags (such as Quikrete or Sakrete standard 4,000 PSI concrete mix) contain carefully proportioned Portland cement, sand, and coarse aggregate gravel. When mixed with clean water, dry bags yield the following verified volumes:

80 lb Concrete Bag: Yields 0.60 cubic feet of placed concrete. It takes 45 bags to equal exactly 1 cubic yard.
60 lb Concrete Bag: Yields 0.45 cubic feet of placed concrete. It takes 60 bags to equal exactly 1 cubic yard.
40 lb Concrete Bag: Yields 0.30 cubic feet of placed concrete. It takes 90 bags to equal exactly 1 cubic yard.

Because an 80 lb bag yields 33% more volume than a 60 lb bag, choosing 80 lb sacks significantly reduces total bag handling, mixing cycles, and empty sack disposal—though an electric concrete drum mixer is strongly recommended.

When to Hand-Mix Bags vs. Ordering a Ready-Mix Truck

Pouring a 10×10 slab represents the exact boundary threshold between mixing bagged concrete on-site and ordering ready-mix delivery from a local batch plant:

Pouring with Bags (1.36 yd³ / 62 bags): Sacks cost approximately $6.00 to $7.50 each ($370 – $460 total materials). This approach is ideal for backyards with zero truck access, narrow gates, steep slopes, or DIYers pacing the pour over a weekend with rented mixing equipment.
Ordering a Ready-Mix Delivery Truck: Ready-mix concrete costs roughly $140 to $170 per cubic yard ($190 – $230 for 1.36 yards). However, nearly all concrete dispatch plants charge a short-load fee of $150 to $300 on orders under 4 to 5 cubic yards. Unless you are pouring an adjoining walkway or footing concurrently, total delivery cost will run $450 to $600—virtually identical in price, but saving 3+ hours of backbreaking manual mixing.

Slab Concrete Volume & Exact Bag Count Quick-Reference Chart

Exact volume in cubic yards and pre-mix bag counts (including 10% contingency allowance) across standard residential slab dimensions at 4-inch patio depth and 6-inch vehicle/shed depth:

Slab Dimension (ft)	Surface Area	4" Depth (yd³ +10%)	4" Depth (80lb Bags)	4" Depth (60lb Bags)	6" Depth (yd³ +10%)	6" Depth (80lb Bags)	6" Depth (60lb Bags)
8 × 8 ft Slab	64 sq ft	0.87 yd³	40 bags	53 bags	1.31 yd³	59 bags	79 bags
8 × 10 ft Slab	80 sq ft	1.09 yd³	49 bags	66 bags	1.63 yd³	74 bags	99 bags
10 × 10 ft Slab	100 sq ft	1.36 yd³	62 bags	82 bags	2.04 yd³	92 bags	123 bags
10 × 12 ft Slab	120 sq ft	1.63 yd³	74 bags	98 bags	2.44 yd³	110 bags	147 bags
12 × 12 ft Slab	144 sq ft	1.96 yd³	88 bags	118 bags	2.93 yd³	132 bags	176 bags
16 × 20 ft Patio	320 sq ft	4.35 yd³	196 bags	261 bags	6.52 yd³	294 bags	392 bags
20 × 20 ft Pad	400 sq ft	5.43 yd³	245 bags	326 bags	8.15 yd³	367 bags	489 bags

Calculations assume standard 4,000 PSI concrete mix yields: 80 lb bag = 0.60 cu ft, 60 lb bag = 0.45 cu ft. 10% allowance covers standard subgrade unevenness and form deflection.

Run custom slab thickness, footing, and column calculations on our Concrete Calculator →

Slab Cost Estimator: Need total project pricing including crushed gravel base, rebar reinforcement grids, and labor? Check out the Concrete Slab Cost Calculator.

Frequently Asked Questions

How many 80lb bags of concrete do I need for a 10x10 slab at 4 inches thick?

You need 62 bags of 80 lb concrete. The slab has a net volume of 33.3 cubic feet (1.23 cubic yards). Adding a 10% contingency allowance for subgrade grading and spillage brings total volume to 36.8 cubic feet (1.36 cubic yards), which divided by 0.60 cu ft per 80 lb bag equals 62 bags.

How many 60lb bags of concrete do I need for a 10x10 slab?

At 4 inches thick with 10% waste, you need 82 bags of 60 lb concrete. At 6 inches thick, you will need 123 bags of 60 lb concrete.

Should a 10x10 concrete slab be 4 inches or 6 inches thick?

A 4-inch depth is standard and structurally sufficient for outdoor patios, sidewalks, trash bin pads, and lightweight tool sheds up to 10×10 ft. Use a 6-inch depth with welded wire mesh or #4 rebar if the slab will support hot tubs, vehicle parking, heavy masonry equipment, or large storage buildings.

How much water do you add to an 80lb bag of concrete?

Add approximately 3 quarts (2.8 liters) of clean water per 80 lb bag. Avoid overwatering; excess water dilutes the cement paste and severely reduces final compressive strength, increasing surface flaking and hairline cracks.

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