How Much Concrete for a 4x6 Pad?
Concrete needed
0.33 cubic yards
A 4 by 6 foot pad at four inches, with ten percent on top for waste.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Length4 ft
- Width6 ft
- Thickness4 in
- Waste allowance10 %
Concrete needed0.33 cubic yards
| Volume | 8 cu ft |
|---|---|
| Cubic yards before waste | 0.3 |
| Cubic yards with 10% waste | 0.33order to this number |
| Order in quarter yards | 0.5 cu yd |
| 60 lb bags, if bagging it | 20 |
| 80 lb bags, if bagging it | 15 |
The material list this produces
| Ready mix concrete, cubic yards | 0.5 |
|---|---|
| Rebar or mesh, sq ft of slab | 24 |
| Form lumber, linear ft | 20 |
Thickness compared
Thickness is the one number on this page worth arguing about, so here is the same slab at each of the usual four.
| Thickness | Concrete needed |
|---|---|
| 4 in | 0.33 cubic yards |
| 5 in | 0.41 cubic yards |
| 6 in | 0.49 cubic yards |
| 8 in | 0.65 cubic yards |
What else matters here
Four by six is the standard standby generator pad, and a generator pad has one requirement a plain slab does not: the conduit has to come up through it, in the right place, before any concrete is poured.
Cast the sleeves in. A length of PVC stubbed up where the electrical and the gas line enter the unit, set and braced before the pour, costs nothing. Core drilling the same holes afterwards costs a morning and a rented drill, and it is the single most common thing forgotten on this pad.
Check the generator's own drawing for the footprint and the required overhang. Most manufacturers want the pad a few inches larger than the unit on all sides, and some specify a thickness or a base spec that is theirs rather than the code minimum.
What this calculator assumes
- One cubic yard is 27 cubic feet. A 4 inch slab is one third of a foot thick, not 4.
- A 60 lb bag yields about 0.45 cubic feet and an 80 lb bag about 0.60. Bags are for small pours only; past about one cubic yard, ready mix is cheaper and far less work.
- Ready mix is usually sold in quarter yard steps with a short load fee below one yard.
Questions people ask
How many bags of concrete for a 4x6 pad?
About 20 sixty pound bags or 15 eighty pound bags at 4 inches thick, waste included.
How thick should a generator pad be?
Four inches suits most residential standby units, but check the manufacturer's drawing. Some specify more, and some specify the base under it as well.
Should conduit be cast into the pad?
Yes. Stub the sleeves up where the electrical and gas enter the unit and brace them before the pour. Drilling them afterwards is far more work.
The concrete calculator takes any dimensions you like and hands back the same list.