Concrete stair calculator: how much concrete do I need for steps?
22 bags
12.8 cu ft · 0.48 cubic yards · 3 steps rising 21 in · for 3 steps of 7 × 11 in, 4 ft wide
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Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
22 bags
12.8 cu ft · 0.48 cubic yards · 3 steps rising 21 in
Three solid concrete steps 4 ft wide, with 7 inch risers and 11 inch treads, take 12.8 cubic feet of concrete, 0.48 cubic yards, which is 22 bags of 80 lb mix at 0.60 cubic feet a bag.
A worked example
Four steps 5 1/2 ft wide with 7 1/4 in risers and 10 1/2 in treads, plus a 36 in landing at the top, in 80 lb bags, needs 115 bags of 80 lb, 2.56 cubic yards. The steps are 5.5 ft × 0.875 ft × 0.604 ft × (4 × 5 ÷ 2) = 29.1 cubic feet, and the landing 5.5 × 3 × 2.42 ft = 39.9, for 69.0 cubic feet in all, 2.56 cubic yards. At 0.60 cubic feet a bag that is 114.9 bags, rounded up to 115: the landing holds more concrete than the four steps.
What size should concrete steps be?
For stairs serving a house, IRC 2021 R311.7.5 sets a riser of no more than 7 3/4 inches and a tread of at least 10 inches, with risers and treads within 3/8 inch of each other in one flight. Divide the total height from the ground to the door threshold by 7.75 and round up to get the number of risers. The calculator marks a riser or tread outside those limits, and the stair calculator works the whole flight out from the total rise.
How much concrete is a landing at the top of steps?
A landing is a slab the full height of the stairs: its width times its depth times the total rise. In front of a door, 36 inches deep at a total rise of 21 inches and 4 ft wide is 4 × 3 × 1.75 = 21 cubic feet, more than the three steps below it. Enter the landing depth above and the calculator adds it.
What else it is called
Concrete stairs are also called concrete steps or a stoop, and the top landing a porch slab. Small runs are poured from bags; from about a cubic yard, 45 bags of 80 lb, ready-mix is ordered by the cubic yard, so the calculator gives both.
Common sizes
| Steps | 3 ft wide | 4 ft wide | 5 ft wide |
|---|---|---|---|
| 1 step, 7 in rise | 1.60 cu ft · 3 bags | 2.14 cu ft · 4 bags | 2.67 cu ft · 5 bags |
| 2 steps, 14 in rise | 4.81 cu ft · 9 bags | 6.42 cu ft · 11 bags | 8.02 cu ft · 14 bags |
| 3 steps, 21 in rise | 9.63 cu ft · 17 bags | 12.83 cu ft · 22 bags | 16.04 cu ft · 27 bags |
| 4 steps, 28 in rise | 16.04 cu ft · 27 bags | 21.39 cu ft · 36 bags | 26.74 cu ft · 45 bags |
| 5 steps, 35 in rise | 24.06 cu ft · 41 bags | 32.08 cu ft · 54 bags | 40.10 cu ft · 67 bags |
| 6 steps, 42 in rise | 33.69 cu ft · 57 bags | 44.92 cu ft · 75 bags | 56.15 cu ft · 94 bags |
Solid steps on grade with 7 in risers and 11 in treads, no landing. Bags are 80 lb at 0.60 cu ft, rounded up.
Where the numbers come from
- Bag yields: QUIKRETE Concrete Mix technical data sheet, document 1101. A 40 lb bag yields approximately 0.30 cu ft, 60 lb 0.45 and 80 lb 0.60. Read October 15, 2026. Data sheet (PDF)
- Riser and tread limits: IRC 2021 R311.7.5.1, riser height not more than 7 3/4 in, and R311.7.5.2, tread depth not less than 10 in, the same rules as the stair calculator. Read October 1, 2026. Source
- The volume is geometry: solid steps poured on grade are stacked blocks, so the first step is one riser high, the second two, and so on. Volume = width × tread × riser × n(n + 1) ÷ 2 for n steps, plus a landing behind the top step at the full height. 1 cubic yard = 27 cubic feet.
This is solid steps on grade, filled to the ground under every tread. Steps formed over a gravel fill or as a sloped slab with a void underneath take less concrete; a footing under the steps is extra and is calculated as a slab. Bag counts are rounded up.
By Javier Miralles · Last updated . How this site is made.
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