Concrete Stairs Calculator — Volume & Bag Count
Enter the number of steps, the rise and run of each step and the stair width to get the total concrete volume and how many bags to buy.
Units
cm
cm
m
4.351 yd³ • 117.5 ft³
3.33 m³
4.35 yd³- 1
Triangular sum
10 × (10 + 1) ÷ 2 = 55Sum 1 + 2 + … + n — each step i sits on top of i risers. - 2
Step block area
0.18 m × 0.28 m = 0.0504 - 3
Volume
1.2 m × 0.0504 m² × 55 = 3.326
How does this calculator work?
Concrete stairs volume = Width × Rise × Run × n(n+1)/2. For 10 steps of 18 cm rise, 28 cm run and 1.2 m width: 1.2 × 0.18 × 0.28 × 55 ≈ 3.33 m³ (≈ 4.36 yd³). Divide by 0.022 yd³ per 80 lb bag for bag count; add 5–10% for waste.
Formula
How this is calculated
A solid concrete staircase is built as a series of stacked rectangular blocks. Looking at the structure from the side, each step i (counting from the bottom) contributes a block of width × run × (i × rise) — the full accumulated height up to that step. Summing from i = 1 to n gives: Volume = width × run × rise × (1 + 2 + … + n) = width × run × rise × n(n+1)/2, where n is the total number of steps, rise is the vertical height of a single step and run is the horizontal depth of a single tread.
In metric mode the rise and run are entered in centimetres and converted to metres before multiplying; the width is entered directly in metres. In imperial mode the rise and run are in inches and converted to metres, while the width is in feet and also converted. The final volume is shown in cubic metres and cubic yards (1 yd³ = 0.7646 m³). Bag counts use published yields of 0.60 ft³ per 80 lb bag and 0.45 ft³ per 60 lb bag.
This formula assumes a solid-filled staircase (no hollow core). Real installations often use earthfill or a timber frame underneath to reduce the concrete needed; in those cases the actual volume may be much lower. The estimate also excludes the landing slab — calculate that separately as a plain slab.
Frequently asked questions
Residential codes commonly require a rise of 150–190 mm (6–7.5 in) and a run (tread depth) of 250–300 mm (10–12 in). A comfortable rule of thumb is: rise + run ≈ 450 mm (18 in).
No. The calculator covers only the stepped section. Calculate any landing or footing slab separately using the concrete slab calculator and add the volumes together.
Each step sits on top of all the steps below it, so step 1 has height 1×rise, step 2 has 2×rise, and so on. The sum 1 + 2 + … + n = n(n+1)/2 is the triangular number formula, giving the total height factor.
Also known as
TG we-Calculate Editorial Team. (2026). Concrete Stairs Calculator — Volume & Bag Count [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/concrete-stairs-calculator
TG we-Calculate Editorial Team. "Concrete Stairs Calculator — Volume & Bag Count." TG we-Calculate. 2026. https://we-calculate.com/calculator/concrete-stairs-calculator.
TG we-Calculate Editorial Team, "Concrete Stairs Calculator — Volume & Bag Count," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/concrete-stairs-calculator
@misc{wecalculate_concrete_stairs_calculator, title = {Concrete Stairs Calculator — Volume & Bag Count}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/concrete-stairs-calculator}}, year = {2026}, note = {TG we-Calculate} }
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