Concrete Calculator
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Enter all dimensions in the same length unit, including slab thickness and step rise. Slabs and footings are rectangular solids; columns are cylinders. For round tube forms, enter the column diameter (across the tube). Steps are a solid staircase from ground to each tread with equal rises and runs, without a landing or hollow underside. The result estimates quantities only.
Your result
Slab/footing: V = lwh. Column: V = π × (diameter / 2)² × height. Solid steps: V = width × rise × run × n(n + 1)/2. Multiply by count, then add waste: ordered = net × (1 + waste/100). yd³ = ft³/27; m³ = ft³ × 0.3048³. Bags = round up(ordered ft³ / yield).
Primary source: QUIKRETE Concrete Mix No. 1101 data sheet, read 2026-10-04.
Worked example
A column with a 12 in diameter and 4 ft height uses inches for both dimensions: diameter 12 and height 48. V = π × (12 / 2)² × 48 = 5428.672105403 in³ = 3.141592654 ft³ = 0.116355283 yd³. Adding 10% gives 3.455751919 ft³ = 0.127990812 yd³. Choose 12 × 40 lb, 8 × 60 lb, or 6 × 80 lb bags.
| Bag | Yield |
|---|---|
| 40 lb | 0.30 ft³ |
| 60 lb | 0.45 ft³ |
| 80 lb | 0.60 ft³ |
These are alternative bag sizes, not quantities to combine. Other mixes can have different yields. Geometry follows the Massachusetts DESE volume formulas; the steps formula sums n stacked rectangular layers.
How to use this tool
Enter your values, choose the options, and select Calculate to see the result and formula.
Frequently asked questions
What yields are used for the bags?
QUIKRETE Concrete Mix No. 1101 publishes approximate yields of 0.30 ft³ for 40 lb, 0.45 ft³ for 60 lb and 0.60 ft³ for 80 lb. Counts include the selected waste and round up to whole bags.
Can I enter feet and inches together?
All dimensions use one selected unit. For a 4-inch slab, either convert to 0.333333333 feet or select inches and enter every dimension in inches.
What kind of steps are included?
Solid steps with equal rise and run, filled to ground underneath every tread. Landings, hollow stairs and supporting structures are excluded.