How it’s calculated
Solid poured steps are a stack of blocks: the first step is 1 rise tall, the second 2 rises, and so on, each one run deep. Summing them gives the triangular-number formula. A top landing is a block at full height.
Example: 3 steps, 7 in rise, 11 in run, 4 ft wide: 4 × (11/12) × (7/12) × 6 = 12.83 ft³. With 10% waste: 14.12 ft³ = 0.523 yd³, or ⌈14.12 ÷ 0.60⌉ = 24 bags of 80 lb mix.
This assumes steps poured solid down to grade. Steps poured over a sloped fill or with a hollow core use less.
Frequently asked questions
How many bags of concrete do I need for 3 steps?
For 4 ft wide steps with a 7 in rise and 11 in run, about 12.8 ft³ (14.1 ft³ with 10% waste), or roughly 24 bags of 80 lb mix.
What is a standard step rise and run?
Many residential codes allow a maximum riser of about 7¾ in and a minimum tread of about 10 in. Exterior steps are often 6–7 in rise with 11–12 in treads. Always check your local code.
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Sources
- QUIKRETE Concrete Mix product data sheet (bag yields) — QUIKRETE Companies
- Topics in Concrete — American Concrete Institute
- NIST Handbook 44, Appendix C: Units of Measurement — U.S. National Institute of Standards and Technology
Formulas are taken from the free public references above. Results are provided “as is” for informational and educational purposes only. See our disclaimer.
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