Work out how many cubic yards, cubic meters, or bags of concrete you need for a slab, footing, post hole, or column — plus an instant cost comparison between bagged mix and ready-mix delivery.
Every shape
Slabs, footings, columns, circular pads & stairs
Bags or yards
40, 60 & 80 lb bag counts, or cubic yard orders
Cost compare
See bagged DIY vs. ready-mix delivered cost
You'll need approximately
123
40 lb bags
98
50 lb bags
82
60 lb bags
62
80 lb bags
Cost estimate (optional)
≈ $204 delivered
≈ $403 bagged DIY
Orders under 3–5 cu yd often carry a short-load fee of $50–$150 from ready-mix suppliers — bags may be more economical at this size.
To find the volume of concrete for a slab, footing, or wall, multiply length by width by thickness, then convert to cubic yards.
Volume (cu ft) = Length (ft) × Width (ft) × Thickness (ft)
Cubic Yards = Volume (cu ft) ÷ 27
A 10 ft × 10 ft slab poured 4 inches thick:
Break an irregular shape into rectangles or circles, calculate each section separately, then add the volumes together.
For a sloped slab, use the average thickness: (min thickness + max thickness) ÷ 2.
| Project | Standard thickness |
|---|---|
| Sidewalks / walkways | 4 in (10 cm) |
| Driveways | 4–6 in (10–15 cm) |
| Garage floors | 4–6 in (10–15 cm) |
| Patios | 4 in (10 cm) |
| Footings | Varies by frost depth & local code |
Always add 5–10% extra to account for spillage, uneven subgrade, and measurement variance — order short and a cold joint can compromise the pour.
Best under roughly 0.5–1 cubic yard — small patios, repairs, post holes, and steps. Higher cost per yard, but no delivery minimum or short-load fee, and you mix only what you need.
Far cheaper per yard once you're above ~1 cubic yard — driveways, garage floors, larger patios. Most suppliers have a minimum order and charge a short-load fee under 3–5 yards.
Mild climates (no hard freezes)
3,000–4,000 PSI mix without air entrainment is generally adequate for residential slabs and driveways.
Freeze-thaw climates
Use 4,000+ PSI with air entrainment to resist surface scaling from freeze-thaw cycles and de-icing salt. Ask your supplier to confirm air entrainment for exterior pours.