For a solid stepped block. This volume model fills all space below each tread; it does not model a thin reinforced stair slab.
- Width, rise and going
- Common width, vertical rise of each step and horizontal depth of an ordinary tread.
- Step count and platform
- Number of rises. An optional top platform replaces the last ordinary tread depth.
Without a platform, all tread depths are equal. With a platform, its depth is at least one going; it extends the full top level of the solid block.
- Net, extra and required concrete; total rise and footprint depth.
Three equal rises, first without a top platform.
| Quantity | Value |
|---|---|
| Width; rise; going | 1 m; 0.175 m; 0.280 m |
| Steps; extra | 3; 10 % |
| Total rise; footprint | 0.525 m; 0.840 m |
| Net; required | 0.294; 0.323 m³ |
For n equal steps: volume = width × rise × going × n(n + 1)/2. This adds the three full-depth step blocks.
Replacing the top tread with a 0.900 m platform gives a footprint of 1.460 m and net volume of 0.6195 m³; with 10% extra, 0.68145 m³ (0.681 m³ displayed).
Ready-mix planning uses the required volume and a truck capacity you enter. Bagged mix uses the finished yield of one bag; bag weight alone does not determine it. Whole bags and loads round up. Optional cost uses your price per volume or per bag.
Bag-count example for a separate slab: 0.660 m³ divided by an assumed yield of 0.020 m³ per bag gives 33 bags. This yield is an example input, not a specification for every 40 kg or 50 kg bag. Check the selected product.
Metric and imperial entry are supported. In these examples, lengths are converted to metres before multiplication; displayed volumes are rounded to three decimals. The arithmetic retains the unrounded value.
The extra percentage is a chosen allowance for this estimate. It is not a required building-code value. Geometry estimates quantity; it does not select concrete strength, foundation depth or reinforcement.
A sloping underside, hollow fill and a separate base slab are outside this shape. The calculator does not choose a suitable rise or going.
Is this the stair layout calculator?
This tool estimates concrete volume. The stair guides explain flights, turns and setting out.
Is the platform an extra step?
No. It replaces the depth of the final tread while keeping the same number of rises.
- Is this the stair layout calculator?
- This tool estimates concrete volume. The stair guides explain flights, turns and setting out.
- Is the platform an extra step?
- No. It replaces the depth of the final tread while keeping the same number of rises.
Measurements, units and material terms
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