The block-volume method
Concrete steps are poured as a stacked pyramid: each step down adds another layer. The quick estimating method treats the whole staircase as a solid triangular prism — width × total run × total rise ÷ 2 — which slightly over-orders but guarantees you don't run short mid-pour. Steps must be poured in one session, so running short is the one mistake you can't fix.
Sizing rules that keep steps legal
Keep risers between 4 and 7.75 inches and treads at least 10 inches deep, and make every riser identical — uneven steps are the number-one trip hazard and the first thing building inspectors measure. For entry steps 4 feet wide and three risers tall, expect roughly 8–10 of the 80-lb bags.
Sources and standards
Where these figures come from
Every formula on this page is implemented from the published reference material below. Where a value depends on a regional code, the calculator lets you override it rather than assuming one jurisdiction.
- ASTM International — C94 for ready-mixed concrete, C150 for cement and C143 for slump testing.
- American Concrete Institute — ACI 318 code requirements and ACI 302 slab construction guidance.
- Portland Cement Association — mix design, yield and curing data published by the US cement industry.
Figures, formulas and reference tables last verified: 19 September 2026.