How Many Bags of Concrete for a 10x10 Slab?
A 10x10 foot concrete slab is the most common size for backyard patios and sheds. The exact number of bags you need depends entirely on the thickness of the pour. This guide breaks down the math for standard 4-inch and heavy-duty 6-inch slabs 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.