How much concrete for a 4 × 4 slab?
A 4 × 4 ft slab (16 sq ft) poured 4 inches thick takes 0.2 cubic yards of concrete. With 10% extra for uneven ground and spillage, order 0.22 cubic yards of ready-mix or buy 10 bags of 80 lb mix.
| Thickness | Exact volume | Order (+10%) | 80 lb bags | 60 lb bags | Typical use |
|---|---|---|---|---|---|
| 4 in | 0.2 yd³ | 0.22 yd³ (0.17 m³) | 10 | 14 | Patio, walkway, shed floor |
| 5 in | 0.25 yd³ | 0.27 yd³ (0.21 m³) | 13 | 17 | Hot tub pad, light driveway |
| 6 in | 0.3 yd³ | 0.33 yd³ (0.25 m³) | 15 | 20 | 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
5.9 cubic feet = 0.22 cubic yards = 0.17 m³. Above about 1 cubic yard, ready-mix delivery is usually cheaper and faster than bags.
Rough material cost (cheapest option)
$37Ready-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 4x4 slab?
At 4 inches thick, 10 bags of 80 lb concrete mix or 14 bags of 60 lb mix, including 10% extra. At 6 inches, 15 bags of 80 lb mix.
Should I use bags or ready-mix for a 4x4 slab?
Bags. At 0.22 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 4 by 4 slab?
Multiply length × width × thickness in feet: 4 × 4 × (4 ÷ 12) = 5.3 cubic feet. Divide by 27 to get 0.2 cubic yards, then add 5–10% extra.