How Many Bags of Concrete for a 10×10 Slab?

The quick answer

A 10 × 10 ft slab poured 4 inches thick holds 33.3 cubic feet (1.23 cubic yards) of concrete. That's 56 bags of 80 lb concrete mix, 75 bags of 60 lb or 112 bags of 40 lb. Add 10% for spillage and an uneven base, and you should buy 62 bags of 80 lb or 82 bags of 60 lb.

Thicker slabs need a lot more. At 6 inches, the same 10 × 10 pad takes 92 bags of 80 lb mix. You can check any size, thickness or bag type in our concrete calculator. It also adds rebar and the cost.

How the math works

Work it out in three steps:

• Find the volume. Length × width × thickness, all in feet: 10 × 10 × (4 ÷ 12) = 33.3 cubic feet. Divide by 27 to get cubic yards: 33.3 ÷ 27 = 1.23 cu yd.
• Divide by the bag yield. According to Quikrete's Concrete Mix data sheet, an 80 lb bag yields about 0.60 cu ft, a 60 lb bag about 0.45 cu ft and a 40 lb bag about 0.30 cu ft. So 33.3 ÷ 0.60 = 55.6, which rounds up to 56 bags of 80 lb mix.
• Add a margin. Forms bow, the ground is never perfectly level and some concrete always stays in the wheelbarrow. 10% extra turns 56 bags into 62. Returning a few unopened bags is much easier than running out halfway through the pour.

Other brands publish similar yields, but always check the figure printed on the bag. Our guide on how much concrete you need covers the same method for footings and post holes.

Bags for a 10×10 slab at every common thickness

Bag counts below include 10% extra. Volumes are the net amount before waste.

In the US, the International Residential Code (IRC Section R506) sets 3½ inches as the minimum for concrete floors on the ground. Most builders pour 4 inches as standard, because a bump in the base or a low spot in the form can easily eat half an inch.

Don't forget what goes under and inside the slab

The bag count is only part of the shopping list. A slab that lasts also needs:

• A compacted gravel base. The IRC typically calls for a 4-inch base of gravel, sand or crushed stone under slabs. For a 10 × 10 pad that's 1.23 cu yd, or about 1.8 tons of crushed stone including 10% for compaction. Our gravel calculator works it out for other depths and materials.
• Reinforcement. A rebar grid at 18 inches on center needs about 154 ft of bar for a 10 × 10 slab, including 10% for laps. That's eight 20 ft lengths. Welded wire mesh or fiber-reinforced mix are common alternatives on small patios. Set the grid spacing in the concrete calculator to see the length and cost.
• Control joints. The National Ready Mixed Concrete Association recommends joint spacing of 24–36 times the slab thickness, so 8–12 ft for a 4-inch slab (NRMCA, Joints in Concrete Slabs on Grade). A 10 × 10 pad is within that range, but many contractors still cut one joint each way to make four 5 × 5 ft panels and keep any cracks in the joints.
• Forms and a vapor barrier. Forms take four 10 ft lengths of 2×4 for a 4-inch slab, plus stakes. Put polyethylene sheeting under any slab that will be enclosed, such as a shed or workshop floor.

Bags or ready-mix for a 10×10 slab?

A 10 × 10 slab sits right on the line where bagged concrete stops being the obvious choice. Before you load 62 bags into a cart, think about what that means on pour day:

• Weight. 62 bags × 80 lb is nearly 5,000 lb, about 2½ tons, to lift twice: once into the car or truck and once into the mixer.
• Water and time. Quikrete calls for about 6 pints (2.8 L) of water per 80 lb bag, so roughly 46 gallons in total. A rented drum mixer usually takes two bags per batch, which means about 30 batches. You need to place each batch before the edge of the previous one starts to set.
• Help. Plan on at least three people: one mixing, one wheeling and one spreading and screeding.

Cost. At an illustrative $6.50 per 80 lb bag, 62 bags come to about $400. Ready-mix at around $165 per cubic yard is about $250 for the 1½ cu yd most plants would deliver. Many plants add a short-load fee on orders under a few yards, so ask for the full delivered price. For a 4-inch slab the two options often end up close. At 5–6 inches, ready-mix or a rental mini-mixer trailer usually wins on both cost and effort.

For a fuller picture of labor, finishes and site prep, see our breakdown of concrete slab cost per square foot.

Working in metric?

The nearest metric equivalent is a 3 × 3 m slab at 100 mm thick. That's 0.9 m³ of concrete, or 0.99 m³ with 10% extra, which works out to about 87 bags of 25 kg premixed concrete. Bag yields vary more between brands outside the US, so check the coverage printed on the bag. Our concrete calculator switches to metres and 25 kg or 40 kg bags in one click.

Pour-day tips

• Protect your skin. Wet concrete is strongly alkaline and can cause serious chemical burns that you may not feel until hours later. OSHA recommends waterproof gloves, boots tall enough that concrete can't get in and washing any splashes off right away (OSHA, Preventing Skin Problems from Working with Portland Cement).
• Don't add extra water. A soupy mix is easier to pour but ends up weaker and more prone to cracking. Follow the water amount on the bag.
• Keep it moist while it cures. Keep the slab damp or covered with plastic for about the first week. Concrete gains strength slowly, and curing it properly greatly reduces surface cracking and dusting (NRMCA, Curing In-Place Concrete).
• Check the forecast. Avoid pouring if frost is expected in the next few days, or in strong sun and wind that will dry the surface before you can finish it.

Sources & further reading

1. Concrete Mix No. 1101 Data Sheet — Quikrete
2. International Residential Code 2021, Chapter 5: Floors (Section R506) — International Code Council
3. CIP 6: Joints in Concrete Slabs on Grade — National Ready Mixed Concrete Association
4. CIP 11: Curing In-Place Concrete — National Ready Mixed Concrete Association
5. Preventing Skin Problems from Working with Portland Cement (OSHA 3351) — US Occupational Safety and Health Administration