How Many Bags of Concrete for a 5x6 Slab?
A 5 by 6 foot slab at 4 inches holds 10.00 cubic feet of concrete. How many bags of concrete for a 5x6 slab comes to 17 bags of 80 lb mix or 23 of the 60 lb size, before a spare bag or two for waste.
Concrete calculator →How the bag count is figured
- Area: 5 × 6 = 30 sq ft.
- Volume at 4 in: 30 × 0.333 = 10.00 cu ft.
- 80 lb bags: 10.00 ÷ 0.60 = 16.7, round up to 17.
- 60 lb bags: 10.00 ÷ 0.45 = 22.2, round up to 23.
Check the yield printed on your brand’s bag, since it varies a little. The concrete calculator handles other shapes.
Related: How Much Sand for a 5x6 Sandbox?
Bags by thickness for a 5x6 slab
| Thickness | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|
| 3 in | 7.50 | 13 | 17 | 25 |
| 4 in | 10.00 | 17 | 23 | 34 |
| 5 in | 12.50 | 21 | 28 | 42 |
| 6 in | 15.00 | 25 | 34 | 50 |
When bags make sense
Bags win on small pads because there is no delivery or short-load charge. The tradeoff is labor: 17 bags of 80 lb mix is 1,360 pounds to lift, pour and mix. A small drum mixer keeps batches consistent, and a helper keeps the pour moving so the edges do not set before the middle.
Related: How Many Bags of Concrete for a 10x10 Slab?
Prep for a small slab
Dig out sod and soft soil, compact the bottom and add a few inches of compacted gravel. Set 2x4 forms level or with a slight slope for drainage, stake them every couple of feet and check the diagonals so the pad is square. Mix to a stiff, oatmeal-like consistency; extra water makes it easier to place but weaker.
Buying the bags
Most stores stock 40, 60 and 80 lb bags. The 80 lb size means fewer bags to open, while 60 lb bags are easier to carry. Either way, buy a spare or two; a short pour is worse than a leftover bag.
Questions people ask
How many 80 lb bags for a 5x6 slab?
About 17 bags at 4 inches thick.
How many 60 lb bags for a 5x6 slab?
About 23 bags at 4 inches thick.
How many bags for a 5x6 slab 6 inches thick?
About 25 bags of 80 lb mix or 34 of 60 lb.
How much does an 80 lb bag of concrete yield?
About 0.6 cubic feet of mixed concrete.
How thick should the base under the slab be?
About 4 inches of compacted gravel is common for residential slabs, more on soft or poorly drained soil.
Related guides
- How Much Area Does a Yard of Concrete Cover?
- How Many Bags of Concrete in a Yard? 40, 60, 80 lb
- Gravel Base Under a Concrete Slab: Depth and Tons
- How Many Yards in a Concrete Truck? Mixer Sizes
- Concrete Short Load Fee: What It Is and How to Cut It
- 60 lb vs 80 lb Concrete Bags: Yield, Count, and Cost
- Rebar vs Wire Mesh in a Slab: Which One to Use
- How Many Bags of Concrete for a 4x8 Slab?
- How Many Bags of Concrete for a 5x5 Slab?
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