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Solid concrete steps are a stack of blocks: counting from the bottom, each step is one riser taller than the one below it and the top landing is the full height of the stair. The Concrete Steps Calculator adds them up — tread × riser × (1 + 2 + … + (n − 1)) for the steps, plus landing depth × total rise — multiplies by the width and converts cubic inches to cubic feet (÷ 1,728) and cubic yards (÷ 27). It adds a waste allowance and divides by the yields QUIKRETE publishes for its Concrete Mix: 0.60 cu ft per 80 lb bag, 0.45 per 60 lb and 0.30 per 40 lb. It checks the design against the 2021 International Residential Code: risers no taller than 7 3/4 in (R311.7.5.1), treads at least 10 in (R311.7.5.2), a stair at least 36 in wide (R311.7.1), a landing at least 36 in deep (R311.7.6) and a handrail once there are four or more risers (R311.7.8). Four 7 in risers with 11 in treads and a 36 in landing, 4 ft wide, take 40.8 cu ft — 1.66 cubic yards with 10% waste, or 75 bags of 80 lb concrete.
Concrete for solid steps = width × (tread × riser × (1 + 2 + … + (n − 1)) + landing depth × total rise), in cubic inches ÷ 1,728 for cubic feet and ÷ 27 for cubic yards. QUIKRETE Concrete Mix yields 0.60 cu ft per 80 lb bag, 0.45 per 60 lb and 0.30 per 40 lb. The 2021 IRC limits risers to 7 3/4 in (R311.7.5.1), sets treads at 10 in minimum (R311.7.5.2), stairs 36 in wide (R311.7.1), landings 36 in deep (R311.7.6) and a handrail at four or more risers (R311.7.8).
| Risers | 36 in wide | 48 in wide | 60 in wide |
|---|---|---|---|
| 1 | 0.21 yd³ · 10 bags | 0.29 yd³ · 13 bags | 0.36 yd³ · 17 bags |
| 2 | 0.49 yd³ · 23 bags | 0.66 yd³ · 30 bags | 0.82 yd³ · 37 bags |
| 3 | 0.84 yd³ · 38 bags | 1.12 yd³ · 51 bags | 1.40 yd³ · 63 bags |
| 4 | 1.25 yd³ · 57 bags | 1.66 yd³ · 75 bags | 2.08 yd³ · 94 bags |
| 5 | 1.72 yd³ · 78 bags | 2.30 yd³ · 104 bags | 2.87 yd³ · 130 bags |
| 6 | 2.26 yd³ · 102 bags | 3.02 yd³ · 136 bags | 3.77 yd³ · 170 bags |
Treat solid steps as stacked blocks: each step from the bottom is one riser taller than the last. Volume = width × (tread × riser × (1 + 2 + … + (n − 1)) + landing depth × total rise). Four 7 in risers with 11 in treads and a 36 in landing, 4 ft wide, is 40.8 cu ft — 44.9 cu ft or 1.66 cubic yards with 10% waste.
Divide the cubic feet by the bag yield: QUIKRETE Concrete Mix yields 0.60 cu ft per 80 lb bag, 0.45 per 60 lb and 0.30 per 40 lb. 44.9 cu ft is 75 bags of 80 lb. Past about a cubic yard, ready-mix is usually cheaper and easier.
The 2021 IRC limits risers to 7 3/4 in (R311.7.5.1) and requires treads of at least 10 in (R311.7.5.2), with no more than 3/8 in difference between the largest and smallest riser or tread in a flight. Stairs must be at least 36 in wide (R311.7.1).
At an exterior door the IRC requires a landing on each side (R311.3) and a stair landing must be at least as wide as the stair and 36 in deep in the direction of travel (R311.7.6). The calculator treats the top platform as that landing.
Yes, once there are four or more risers (IRC R311.7.8). Handrails go 34 to 38 in above the tread nosings. Also check guards where the walking surface is more than 30 in above the grade below (R312.1.1).
Reinforcing the landing or slab? The rebar calculator counts bars each way, 20 ft sticks and weight.
Brick-faced steps? The brick calculator and mortar calculator count the units and bags.
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