How to use the concrete steps calculator
Poured concrete steps look simple, but the volume climbs quickly because each step sits on top of the ones below it. This calculator adds up the solid blocks under every tread so you can order the right amount of ready-mix or bags for front steps, garden steps, a back door stoop or steps down to a patio.
- Enter the number of steps (risers) from the ground to the top surface.
- Enter the rise per step and the tread depth. If you only know the total height, divide it by the number of steps, or use the stair calculator to pick an even rise first.
- Enter the width of the steps from side to side.
- Add a top landing if the top step is a platform deeper than one tread, such as a stoop outside a door.
- Set waste at 5–10% for spillage, uneven ground and formwork bowing.
Concrete steps formula
Step i (from the bottom) = width × (i × rise) × depth
Volume = width × rise × Σ i × depthᵢ
Without a landing: volume = width × rise × tread × n(n + 1) ÷ 2
Order = volume × (1 + waste) · bags = ⌈order ÷ bag yield⌉
Here n is the number of steps, and depthᵢ is the tread depth for every step except the top one, which takes the landing depth when you enter one. The result is for solid steps on prepared ground; footings, slabs below and any fill are extra.
| Bag size | Typical yield | Bags per yd³ (approx.) |
|---|---|---|
| 40 lb | 0.30 ft³ | 90 |
| 60 lb | 0.45 ft³ | 60 |
| 80 lb | 0.60 ft³ | 45 |
| 25 kg | about 0.013 m³ | about 77 per m³ |
Worked examples
Three garden steps in US units
Three steps 36 in wide with a 7 in rise and an 11 in tread: 3 × (7 ÷ 12) × (11 ÷ 12) × (1 + 2 + 3) = 9.63 ft³, or 0.36 yd³. With 10% waste the order is 10.59 ft³, which is 18 bags of 80 lb mix.
Front door stoop with a landing
The same three steps with a 36 in deep landing on top: the depths are 11, 11 and 36 in, so the sum is 1 × 11 + 2 × 11 + 3 × 36 = 141 in. Volume = 3 × (7 ÷ 12) × (141 ÷ 12) = 20.56 ft³, or 0.76 yd³, and 22.6 ft³ with waste. The landing more than doubles the concrete, so this is where a fill core or a small ready-mix load starts to pay off.
Metric steps
Four steps 1,200 mm wide with a 170 mm rise and a 280 mm going: 1.2 × 0.17 × 0.28 × 10 = 0.571 m³, and 0.628 m³ with 10% waste. That is about 49 bags of 25 kg mix, so most builders would order ready-mix.
Who this calculator helps
- Architects and landscape designers checking quantities for entrance steps, terraces and garden level changes.
- Contractors and estimators pricing a small pour and deciding between bags and ready-mix.
- Homeowners and DIY builders planning a stoop or garden steps before they build the formwork.
- Students learning how stepped volumes are taken off for an estimate.
Practical tips
- Keep every riser the same height. Uneven risers are a common trip hazard, and codes limit the variation between them.
- Slope each tread about 1/4 in per foot (around 2%) toward the front so rain runs off, and give the top a broom finish for grip.
- Use the concrete calculator for the footing or slab under the steps, the rebar calculator for reinforcement and the ramp slope calculator if you also need step-free access.
- For a gentle slope across a garden, the paver calculator may suit landings between steps better than solid concrete.
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