How to use the concrete stairs calculator
Prepare the values for this calculation
Estimate concrete for a simplified stair wedge plus entered landing volume. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Stair width (ft): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Total rise (ft): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Total run (ft): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Landing volume (ft³): enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Waste allowance (%): enter a value at least 0 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Concrete required first. With the unchanged example inputs, it is 3.2593 yd³. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Stair width (ft) from 4 to 4.4. The resulting Concrete required is 3.5852 yd³. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Concrete Stairs Calculator formula
Stair body volume = ½ × total rise × total run × width; landing volume is added, then waste is applied.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Stair width (ft) | minimum 0 | 4 |
| Total rise (ft) | minimum 0 | 5 |
| Total run (ft) | minimum 0 | 8 |
| Landing volume (ft³) | minimum 0 | 0 |
| Waste allowance (%) | minimum 0; maximum 100 | 10 |
Worked example
Using the example inputs above, the concrete required is 3.2593 yd³.
- Concrete required
- 3.2593 yd³
- Stair wedge volume
- 80 ft³
- Total with waste
- 88 ft³
Results and assumptions
This models the stair body as a triangular prism plus an entered landing volume; actual formed stair geometry may require a more detailed takeoff.
Fix an input or unexpected result
Stair width (ft) is required. Enter stair width (ft) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.