# Concrete Stairs Calculator

URL: https://speedycalculator.com/calculators/construction/concrete-stairs/
Last updated: 2026-10-25

> The concrete stairs calculator finds the concrete volume for solid poured steps with an optional top platform from the number of steps, riser height, tread depth and width, in yards, metres and bags.

## Inputs

- Number of steps
- Riser height (in, cm, mm, ft, m)
- Tread depth (run) (in, cm, mm, ft, m)
- Stair width (ft, m, in, yd, cm)
- Top platform depth (0 if none) (ft, m, in, yd, cm)
- Waste (%)
- Premix bag size
- Price per bag (/piece)
- Ready-mix price (/yd³, /m³, /ft³)

## Results

- Concrete needed
- Total rise
- Total run (incl. platform)
- Weight
- Premix bags
- Cost with bags
- Cost with ready-mix

## Formula

```
V = W × [T × R × n (n + 1) ÷ 2 + P × R × n]
with n steps, riser R, tread T, width W and top platform depth P
```

## Explanation

Solid concrete steps are poured as a single block, with each step stacked on the one below. The volume grows quickly with each extra step, so a five-step stoop can need more than a cubic yard. A landing (platform) at the top in front of the door is usually at least 36 in deep.

### How to use the Concrete Stairs Calculator

- **Number of steps**
- **Riser height**
- **Tread depth (run)**
- **Stair width**
- **Top platform depth (0 if none)**
- **Waste**
- **Premix bag size**
- **Price per bag**
- **Ready-mix price**
- Every result field is editable: type into **Concrete needed** and **Stair width** plus every other field update to match.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the number of steps, riser height, tread depth, stair width and the depth of any top platform, plus waste, bag size and prices. The calculator adds the volume of every stacked step and the platform.

### Premixed bag yields

BagYieldBags per yd³40 lb0.30 ft³9050 lb0.375 ft³7260 lb0.45 ft³6080 lb0.60 ft³4525 kg≈ 0.0117 m³≈ 85 per m³

### Tips for an accurate estimate

- Measure the formwork, not the drawing – forms bulge and subgrades are rarely perfectly flat, so add 5–10%.
- Below about 1 cubic yard, premixed bags are usually cheaper; above that, ready-mix saves time and gives a more consistent pour.
- Order ready-mix in quarter- or half-yard steps and ask about short-load fees for small deliveries.
- Keep fresh concrete damp for at least a week – curing matters as much as the mix for final strength.

### Common mistakes to avoid

- Running short mid-pour, which leaves a weak cold joint.
- Adding extra water on site to make concrete easier to place – it lowers strength and increases cracking.
- Ignoring the volume of rebar, posts or pipes in the pour, or the gravel base under it.

### Inputs explained

FieldWhat to enterNumber of stepsA numberRiser heightUnits: in, cm, mm, ft, mTread depth (run)Units: in, cm, mm, ft, mStair widthUnits: ft, m, in, yd, cmTop platform depth (0 if none)Units: ft, m, in, yd, cmWasteIn %Premix bag sizeChoose one: 40 lb bag (0.30 ft³), 50 lb bag (0.375 ft³), 60 lb bag (0.45 ft³), 80 lb bag (0.60 ft³) …Price per bagUnits: /pieceReady-mix priceUnits: /yd³, /m³, /ft³

### What each result means

- **Concrete needed** = [Stair width]×([Tread depth (run)]×[Riser height]×[Number of steps]×([Number of steps] + 1)÷2 + [Top platform depth (0 if none)]×[Riser height]×[Number of steps])×(1 + [Waste]÷100)
- **Total rise** = [Number of steps]×[Riser height]
- **Total run (incl. platform)** = [Number of steps]×[Tread depth (run)] + [Top platform depth (0 if none)]
- **Weight** = [Concrete needed]×2400
- **Premix bags** = ceil([Concrete needed]÷[Premix bag size])
- **Cost with bags** = [Premix bags]×[Price per bag]
- **Cost with ready-mix** = [Concrete needed]×[Ready-mix price]

## Worked example

Inputs — Number of steps: 4; Riser height: 7 in; Tread depth (run): 11 in; Stair width: 4 ft; Top platform depth (0 if none): 3 ft; Waste: 7 %; Premix bag size: 80 lb bag (0.60 ft³); Price per bag: $6.5 /piece; Ready-mix price: $150 /yd³.

Results — **Concrete needed = 1.957 yd³**; Total rise = 28 in; Total run (incl. platform) = 6.67 ft; Weight = 7,918 lb; Premix bags = 89; Cost with bags = $578.50; Cost with ready-mix = $293.59.

## FAQ

**How much concrete for 3 steps?**
With 7 in risers, 11 in treads and a 4 ft width, about 8.0 ft³ (0.3 yd³) without a platform.

**What are standard step dimensions?**
Risers 4–7¾ in and treads at least 10–11 in (IRC). Keep all risers within ⅜ in of each other.

**Can I reduce the concrete?**
Fill the core with compacted gravel or rubble, leaving at least 4 in of concrete on every face.

**What formula does the Concrete Stairs Calculator use?**
V = W × [T × R × n (n + 1) ÷ 2 + P × R × n].


## Sources

- [International Code Council – IRC R311.7.5 Stair treads and risers](https://codes.iccsafe.org/)