A 10×10 ft slab is one of the most common concrete projects for homeowners — used for sheds, small patios, utility pads, and hot tub bases. Knowing exactly how much concrete to order (or how many bags to buy) before you start saves a wasted trip to the store and prevents the concrete from setting before you've filled the form. Here are the exact numbers.
10×10 Slab Concrete Requirements
| Thickness | Cubic Yards | +10% Waste | 80lb Bags | +10% Waste |
|---|---|---|---|---|
| 4 inches | 1.23 yd³ | 1.35 yd³ | 56 bags | 62 bags |
| 5 inches | 1.54 yd³ | 1.69 yd³ | 69 bags | 76 bags |
| 6 inches | 1.85 yd³ | 2.04 yd³ | 83 bags | 92 bags |
80lb bag yield ≈ 0.60 cu ft (per Quikrete® and Sakrete® specifications). Bag count rounded up to the nearest whole bag.
The Formula
For a 10×10 at 4 inches: (10 × 10 × 4/12) ÷ 27 = 33.33 ÷ 27 = 1.23 yd³. Always add 5–10% for waste.
Bags vs. Ready-Mix Concrete
Pre-Mixed Bags
- ✓ No minimum order
- ✓ Work at your own pace (mix in batches)
- ✓ Available at any home center
- ✗ Labor-intensive for larger slabs
- ✗ Harder to achieve consistent mix
- ✗ More expensive per yard for big pours
Ready-Mix (Truck Delivery)
- ✓ Consistent, high-quality mix
- ✓ Fast to pour large volumes
- ✓ More economical per yard over ~1.5 yd³
- ✗ Minimum order (typically 1 yd³)
- ✗ Must pour entire batch quickly
- ✗ Requires site access for truck
For a 10×10 at 4 inches (1.23 yd³), either option is practical. Use bags for flexibility; use ready-mix for speed and structural consistency.
Why the Waste Factor Matters
A flat, perfectly formed 10×10 slab in theory needs exactly 1.23 yd³. In practice, subgrade is rarely perfectly level, forms flex slightly, and some concrete spills. Running short mid-pour forces an emergency bag run — or worse, you pour a cold joint. Order 10% extra (1.35 yd³ / about 62 bags) for peace of mind.
Calculate Any Slab Size
The concrete calculator supports slabs, footings, and columns — with live cubic yard, 60lb bag, and 80lb bag counts. Adjust the waste factor and copy the supplier summary directly.
Open the Concrete Calculator →Frequently Asked Questions
How much concrete do I need for a 10×10 slab at 4 inches?
(10 × 10 × 4/12) ÷ 27 = 1.23 cubic yards. With a 10% waste factor, order 1.35 yd³. That's approximately 56 × 80lb pre-mixed bags if you're not using ready-mix.
How many 80lb bags of concrete for a 10×10 slab?
At 4 inches thick: approximately 56 bags (base) or 62 bags (with 10% waste). At 5 inches: 70 bags / 77 with waste. At 6 inches: 83 bags / 91 with waste. Each 80lb bag yields ≈ 0.60 cu ft.
Should I use ready-mix or bags for a 10×10 concrete slab?
A 10×10 slab at 4 inches needs about 1.23 yd³ — just above the point where ready-mix becomes practical (most suppliers require a 1 yd³ minimum). For DIY projects, bags are flexible but labor-intensive. Ready-mix is faster and structurally more consistent. Consider ready-mix for anything over 1 yard.
Do I need rebar or wire mesh in a 10×10 concrete slab?
For a basic shed floor or patio slab (no vehicle traffic), 6×6 wire mesh is typical. For a slab that will support a vehicle or heavy load, use #3 or #4 rebar on 12-inch centers. Consult a local contractor for load-bearing applications.
How thick should a concrete slab be for a shed or patio?
For a garden shed, 4 inches is standard. For a garage or workshop slab, 5–6 inches is recommended. Patios are typically 4 inches. Add 10% to your order to account for uneven subgrade, form imprecision, and spillage.
Related Resources
- → Concrete Calculator — slabs, footings, and columns with bag count
- → Gravel Calculator — estimate your gravel base layer first
- → Concrete Bags vs Ready-Mix — which option is right for your pour size?
- → Asphalt Calculator — compare paving options
How This Estimate Was Prepared
All volume estimates on this page use standard area and volume formulas — length × width × depth ÷ 27 for cubic yards. Bag yield figures (0.60 cu ft per 80lb bag, 0.45 cu ft per 60lb bag) are based on published specifications from major concrete bag manufacturers. A 10% waste factor is applied to account for form imprecision, uneven subgrade, and spillage. Always confirm bag yield with the label on your specific product. Last reviewed: May 2026.
Disclaimer: Estimates are for planning only. Actual quantities vary with subgrade conditions, form construction, and mix design. Consult a licensed contractor for structural or load-bearing applications.