Concrete Steps Calculator (Cubic Yards, Bags, Risers & Landing)
How much concrete solid steps need, from the total height to climb: number of risers, riser height, treads, top landing, cubic yards and 80 lb bags.
Formula
Risers n = ⌈total rise ÷ max riser⌉; riser height R = total rise ÷ n. Side profile area = tread × R × n(n − 1) ÷ 2 + landing depth × n × R (each lower tread is a block of its own height; the landing sits at full height). Volume (cu ft) = profile (sq in) × width (in) ÷ 1,728; cubic yards = cu ft × (1 + waste) ÷ 27; bags = cu ft × (1 + waste) ÷ bag yield.
Worked example
Inputs: Total rise (ground to top of landing) = 21 in; Step width = 4 ft; Tread depth = 11 in; Top landing depth (0 = no landing) = 36 in; Max riser height (IRC 7¾ in; check your local code) = 7.75 in; Waste allowance = 10 %; Bag yield (from the bag) = 0.6 cu ft/bag.
| Risers | 3 |
|---|---|
| Riser height in | 7 |
| Treads below landing | 2 |
| Total run in | 58 |
| Cubic feet | 27.42 |
| Cubic yards | 1.12 |
| Bags | 51 |
Solid steps poured on grade; subtract any fill (gravel or block) you place inside the forms.
FAQ
How much concrete for 3 steps?
For a 21 in rise, 4 ft wide steps with 11 in treads and a 36 in landing: 3 risers of 7 in, side profile 11 × 7 × 3 + 36 × 21 = 987 sq in, so 987 × 48 ÷ 1,728 = 27.4 cu ft, about 1.12 cu yd with 10% waste or 51 bags at 0.60 cu ft each.
How tall should each step be?
The IRC limits risers to 7¾ in and requires treads of at least 10 in (Section R311.7). The calculator divides the total rise evenly so every riser is the same height.
Do I need a landing at the door?
The IRC requires a landing at least 36 in deep in the direction of travel at the top of stairs. Enter 0 if the steps lead to an existing slab or porch.
Can I use less concrete?
Yes: many builders fill the inside of the forms with compacted gravel or broken block. Subtract that volume; this calculator assumes solid concrete.
How many bags is a yard?
At 0.60 cu ft per 80 lb bag (QUIKRETE data sheet), 27 ÷ 0.60 = 45 bags per cubic yard. Over about a yard, ready-mix is usually easier than mixing bags.
Sources
- ICC 2021 International Residential Code, Chapter 3, Section R311.7 (stairways: max riser 7¾ in, min tread 10 in)
- QUIKRETE Concrete Mix (No. 1101) data sheet: 80 lb bag yields approx. 0.60 cu ft
- Geometry (volume/area formulas); no external constant needed
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Last reviewed 2026-10-20.