How much concrete for a 6 × 6 slab?
A 6 × 6 ft slab (36 sq ft) poured 4 inches thick takes 0.44 cubic yards of concrete. With 10% extra for uneven ground and spillage, order 0.49 cubic yards of ready-mix or buy 22 bags of 80 lb mix.
| Thickness | Exact volume | Order (+10%) | 80 lb bags | 60 lb bags | Typical use |
|---|---|---|---|---|---|
| 4 in | 0.44 yd³ | 0.49 yd³ (0.37 m³) | 22 | 30 | Patio, walkway, shed floor |
| 5 in | 0.56 yd³ | 0.61 yd³ (0.47 m³) | 28 | 37 | Hot tub pad, light driveway |
| 6 in | 0.67 yd³ | 0.73 yd³ (0.56 m³) | 33 | 44 | Driveway, garage floor |
Bag counts include the 10% extra and assume 0.60 ft³ per 80 lb bag and 0.45 ft³ per 60 lb bag.
Change the size, thickness or price
13.2 cubic feet = 0.49 cubic yards = 0.37 m³. Above about 1 cubic yard, ready-mix delivery is usually cheaper and faster than bags.
Rough material cost (cheapest option)
$83Ready-mix often has a short-load fee under 4–5 yd³. Rough 2026 US prices, edit to match local quotes.
FAQ
How many bags of concrete for a 6x6 slab?
At 4 inches thick, 22 bags of 80 lb concrete mix or 30 bags of 60 lb mix, including 10% extra. At 6 inches, 33 bags of 80 lb mix.
Should I use bags or ready-mix for a 6x6 slab?
Bags. At 0.49 cubic yards the job is small enough to mix by hand or with a rented mixer, and ready-mix suppliers charge a short-load fee for small orders.
How do you calculate concrete for a 6 by 6 slab?
Multiply length × width × thickness in feet: 6 × 6 × (4 ÷ 12) = 12 cubic feet. Divide by 27 to get 0.44 cubic yards, then add 5–10% extra.