Concrete
Concrete Bags Calculator: How Many Bags Do You Need?
Understand concrete bag yields, convert volume into bags, and compare 40, 60 and 80 lb bags (and 20–30 kg bags) with worked examples and a quick reference table.
2 min read
- Dual US / Metric
- +10% Waste Allowance
- Free · Runs in Your Browser
Concrete Stairs Calculator
Poured concrete steps are built as a series of stacked blocks, each one riser taller than the last. Enter the stair width, number of steps, riser height and tread depth to calculate the total volume of solid steps.
Enter your measurements
Enter your measurements and press Calculate to see quantities, a material breakdown and an optional cost estimate.
How the calculation works
- Volume = Width × Tread depth × Riser height × (1 + 2 + … + n)
- 1 + 2 + … + n = n × (n + 1) ÷ 2
- Landing (optional) = Width × Extra depth × (n × Riser height)
Step 1 is one riser tall, step 2 is two risers tall and so on, so the stair is the sum of n stacked blocks. The n(n+1)/2 shortcut adds them up.
Assumptions used
- Stairs are solid concrete poured on grade, not hollow or cantilevered.
- Side walls (cheek walls) and footings are not included.
- Building codes regulate riser height and tread depth; values shown in help text are typical, not universal.
Example calculation
4 ft wide stairs with 4 steps, 7 in risers and 11 in treads, no landing, 10% waste.
- 1Block size: 4 × (11 ÷ 12) × (7 ÷ 12) = 2.14 ft³
- 2Sum of steps: 4 × 5 ÷ 2 = 10
- 3Volume: 2.14 × 10 = 21.4 ft³ (0.79 yd³)
- 4With 10% waste: 23.5 ft³ (0.87 yd³)
Result: About 40 × 80 lb bags, or just under a cubic yard of ready-mix.
How to measure your project
- Total rise is the vertical height from the ground to the top surface (door threshold or landing). Divide it by the number of steps to get the riser height.
- Keep riser heights equal; uneven steps are a trip hazard.
- If the top step is a deeper landing, enter the extra depth beyond a normal tread in the landing field.
Frequently asked questions
What is a standard riser height for concrete steps?
Many residential codes allow a maximum riser of about 7¾ in (197 mm) and a minimum tread of about 10 in (254 mm). Exterior steps often use 6–7 in risers for comfort. Confirm with your local code.
Can I reduce the concrete needed for steps?
Yes. Builders often fill the core of large steps with compacted gravel or rubble before pouring, which reduces concrete volume. This calculator assumes solid steps, so it gives the maximum volume.
Related guides
Results are estimates based on the measurements and assumptions you enter. Always confirm product specifications, local building codes and final quantities with your supplier or a qualified professional. See our disclaimer.