How Many Bags of Concrete for a 10x10 Slab?
A 10×10 foot slab is the standard footprint for backyard patios and sheds. Your bag count depends entirely on thickness. We have framed dozens of these pads. The math changes significantly between a standard 4-inch pour and a heavy-duty 6-inch slab. Exact breakdown below using 80 lb bags.
Use the Concrete Calculator →Steps
- Calculate base volume — Multiply 10 ft × 10 ft × (thickness in ÷ 12). A 4-inch slab = 33.33 ft³; a 6-inch slab = 50 ft³.
- Add 10% waste — Multiply base volume by 1.10. A 4-inch slab becomes 36.67 ft³; a 6-inch slab becomes 55 ft³.
- Convert to 80 lb bags — Divide adjusted volume by 0.60 ft³ per 80 lb bag and round up. Result: 62 bags (4 in) or 92 bags (6 in).
4-inch slab — the standard patio pour
Start with area: 10 ft × 10 ft = 100 ft². Convert 4-inch thickness to feet: 4 ÷ 12 = 0.333 ft.
Base volume = 100 × 0.333 = 33.33 ft³. Add 10% waste for spillage and uneven subgrade: 33.33 × 1.10 = 36.67 ft³.
Each 80 lb bag yields approximately 0.60 ft³. Bags needed = 36.67 ÷ 0.60 = 61.1 → round up to 62 bags.
6-inch slab — heavy-duty option
Same 100 ft² area, but thickness is 6 ÷ 12 = 0.5 ft. Base volume = 100 × 0.5 = 50 ft³.
With 10% waste: 50 × 1.10 = 55 ft³. Bags = 55 ÷ 0.60 = 91.7 → round up to 92 bags of 80 lb mix.
At this volume (about 2 yd³), compare ready-mix delivery quotes — a short-load truck may save significant labor.
Why round up and add waste?
You cannot buy a partial bag, and opened bags on site often go unused. Rounding up prevents a mid-pour store run.
Ten percent waste is the industry standard for flatwork. Irregular excavations or steep grades may need 12–15%.
Verify with the calculator
Enter 10 ft length, 10 ft width, and your chosen thickness in our free concrete calculator for an instant bag count, cubic yard total, and ready-mix comparison.
Frequently asked questions
- How many 80 lb bags for a 10x10 patio at 4 inches?
- About 62 bags. Volume is 10 × 10 × (4 ÷ 12) = 33.33 ft³. With 10% waste that is 36.67 ft³. At 0.60 ft³ per 80 lb bag, divide and round up to 62 bags.
- Should I use 4-inch or 6-inch thickness?
- 4 inches is standard for foot-traffic patios and shed pads. Use 6 inches if the slab will support heavy equipment or vehicle parking.
- When is ready-mix cheaper than bags?
- At roughly 1.5 cubic yards or more, a ready-mix truck is usually faster and often cheaper than hauling 60+ bags. A 10×10 × 4 in slab is about 1.36 yd³ with waste — near the break-even point.