Concrete Stairs Calculator — m, m³, bags, cost
How to use this calculator
Select a stair type (straight, L-shaped, or U-shaped), enter total rise, stair width, riser height, tread depth, and waist slab thickness. Choose the unit (m, cm, or mm) from the dropdown next to each input. Results update instantly with number of risers, total run, stair angle, and concrete volume.
Cost — pick ready-mix per m³, 50 kg bags, or 25 kg bags. Select your currency (EUR, PLN, CZK, etc.).
Reinforcement — main bars along the waist + distribution bars per EN 1992-1-1, B500B rebar.
Labor — rate per step, per m³, or a flat price. Grand total sums all active sections.
Saved Calculations
| Time | Type | Rise | Steps | Vol m³ | Cost | Rebar | Labor | Total |
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How to Calculate Concrete for Stairs (Metric)
This concrete stairs calculator estimates volume in cubic meters, number of pre-mixed bags (25 kg and 50 kg), total weight, material cost, reinforcement, and labor for cast-in-place concrete stairs. Supports straight runs, L-shaped (with one landing), and U-shaped (with two landings) configurations. Enter dimensions and choose the unit (m, cm, or mm) from the dropdown next to each input.
Stair Concrete Volume Formulas
The total concrete volume is the sum of three components: Steps — each step is a triangular prism: 0.5 × riser height × tread depth × width. Waist slab — the structural slab under the stairs: waist thickness × slope length × width, where slope length = √(total rise² + total run²). Landings — for L/U shapes: landing width × landing depth × waist thickness. Number of risers = total rise ÷ riser height (rounded to nearest whole number).
Building Code Requirements (EN 1992-1-1 / Eurocode)
Per Eurocode and national annexes: maximum riser height is 196 mm, minimum tread depth (going) is 254 mm, minimum stair width is 800 mm for residential. The stair angle should be between 30° and 37° for comfortable use. The rule of thumb is 2R + G = 600–650 mm (where R = riser, G = going). Reinforcement uses B500B rebar with 40db lap splices per EN 1992-1-1 §8.7 and concrete cover per exposure class.
FAQ
How thick should the waist slab be? For residential stairs up to 3 m rise, 150 mm is typical. For longer spans or commercial use, 200 mm or more may be needed — consult a structural engineer. A common rule is L/20 to L/25, where L is the slope length.
How much concrete for stairs? A typical straight-run residential staircase (2.7 m rise, 1 m wide, 15 risers) needs approximately 0.8–1.2 m³, which equals roughly 33–50 bags of 50-kg mix.
