Pouring concrete
Pages in this list checked · How we check
Pouring concrete takes 6 of the pages on this site, not one. A slab, a pad or a footing, from the volume to the bag count to what the truck will cost. The waste allowance is the number that decides whether you make a second trip. Each page in the list computes its own figure from a published formula and prints the working, so the whole sequence can be checked rather than trusted.
- 1Concrete CalculatorCubic yards, bags, and the waste allowanceCalculator
- 2Cubic Yard CalculatorAny volume in yards, for material sold by the yardCalculator
- 3Gravel & Aggregate CalculatorThe base course under the slabCalculator
- 4Square Footage CalculatorThe area before you pick a thicknessCalculator
- 5Concrete for a 10 × 10 Slab by ThicknessRead the yardage straight off the thicknessChart
- 6What a Concrete Patio CostsReady-mix against bags, with the crossover pointGuide
What goes wrong on this job
The waste allowance decides the delivery, not the volume
Ready-mix arrives in quarter-yard increments and a short load carries a surcharge. A 10 by 10 slab at 4 in is 1.36 cubic yards with 10% waste, so you order 1.5 and pay for the difference. Bagged concrete rounds the other way and 1.36 yards is 82 sixty-pound bags — a pallet, moved by hand.
Base course before slab thickness
Four inches of compacted gravel under a slab is normal and is a separate order, usually by the ton rather than the yard — under a 10 by 10 slab that is about 1.2 tons. Skipping it does not save concrete; it moves the cost to the crack that appears in the second winter.
It cures, it does not dry
Cement and water react chemically, which is why concrete sets underwater. Walk on it at 24 to 48 hours, drive on it at 7 days, and expect about 70% of design strength at that point. Full strength is quoted at 28 days. Keeping it damp for the first week matters more than the weather afterwards.
A 10 × 10 slab at 4 inches
| Figure | Value |
|---|---|
| Volume | 33.33 cu ft |
| With 10% waste | 36.67 cu ft |
| Cubic yards | 1.36 |
| 60 lb bags | 82 |
| Walk on it | 24–48 h |
| 70% strength | 7 days |
| Design strength | 28 days |
Typical figures for orientation. Every one is recomputed by the calculators above from the dimensions you actually have.
What the figures rest on
Every quantity above is computed by one of the calculators in the list, from these published standards.
- American Concrete Institute
- Portland Cement Association
- NIST Special Publication 811, App. B.9 — cubic yard to cubic meter; the yard is exactly 0.9144 m
- US EPA, Volume-to-Weight Conversion Factors, April 2016 — construction and demolition debris table
- National Stone, Sand & Gravel Association
- USGS Mineral Commodity Summaries — construction aggregates
- ANSI Z765 residential square footage measurement standard
- NIST Office of Weights and Measures