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Concrete steps and stairs calculator

Three solid steps 1m wide with a 170mm rise and a 280mm going need 0.31 m³ including 10% extra: 35 x 20kg bags.

In US sizes three steps 36in wide with a 7in rise and 11in tread is 0.39 yd³ (11 ft³), about 19 x 80lb bags.

1. What are you doing?

2. Your job

Tap to type this size280mmTap to type this size1mTap to type this size170mm3 steps

Tap the going, rise or width on the picture to change it.

3. Sizes

Product

Allmat concrete calculator

35 x 20kg Concrete Mix 20kg

What we'd use

  • Concrete Mix 20kg bag

    Concrete Mix 20kg: 35 bags

You need 0.31 m³ of concrete

0.29 m³ plus extra for spillage and uneven ground (10% on the steps).

Details: other bag sizes, water, weight, getting it home

About 35 x 20kg or 28 x 25kg bags of concrete, our estimate from bag weight.

  • Concrete Mix 20kg (35 × 20 kg): Water: about 61.3 L. Weight: 700kg. Mixer loads at 2 bags a load: 18.

Bags or a truck?

Bags work, or mix your own with Builders Cement, sand and aggregate.

Cement Australia's guide: under 0.1 m³ use bags, 0.1 to 0.5 m³ mix your own, over 0.5 m³ ready-mix. Up to about 1 m³ we still show the bags; past that, and for a house slab or a driveway beyond a small patch, it is a truck pour.

Getting it home

Total weight: 700kg. About 1 ute load at 1,000kg, our estimate.

Click and collect or delivered across Adelaide.

How we worked it out
  • Steps: 0.29 m³ plus 10% = 0.31 m³, which is 35 x 20kg bags.

Cement Australia: about 110 x 20kg bags make 1 m³ (their FAQ, calculator and the PROSTRENGTH Rapid Set data sheet). Rapid Set Concrete publishes no per-m³ figure, so it uses the same 110.

Trade Mortar: about 20 house bricks or 10 masonry blocks per 20kg bag at a 10mm joint (Cement Australia).

Estimates only. Check sizes and quantities against your plans, and with your engineer or builder, before you order.

Pour-day check

Type in the weather for the day you plan to pour. Temperature never changes how much you need; it changes the timing.

  • Concrete Mix 20kg: 20°C is within the maker's range (5°C to 35°C).
  • Keep it damp for 7 days (Cement Australia).
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How the concrete steps calculator works

Solid steps on the ground are stacked blocks: the first step is one rise tall, the second two rises, the third three. Multiply width by going by rise, then by 1 + 2 + 3 for three steps.

In our test of 17 online calculators, three counted only one rise per step and came out at about half. Check for that if you compare answers.

Rise, going and a landing

The rise is the height of each step and the going is the depth of each tread, front to back. A landing at the top is a slab the full height of the steps, so it adds a lot of concrete for its size.

Questions

For steps 1m wide with a 170mm rise and a 280mm going, about 0.31 m³ with 10% extra, or 35 x 20kg bags of Concrete Mix.

The rise is the height of one step. The going is the depth of the tread you stand on.

Check that each step is counted at its full height from the ground. A three-step flight has six rises of concrete in total, not three.

Enter a landing depth if the top step needs room to stand and open a door. Because the landing sits at full height, check the extra concrete it adds before you decide.

Goes with this job

Disclaimer

This calculator gives estimates from the sizes you enter, using manufacturers' published figures and standard geometry. It is not engineering or design advice. Footing, slab and beam sizes must come from your plans or engineer. Allow for site conditions, spillage and uneven ground. Check quantities with your supplier before ordering. Allmat accepts no responsibility for decisions made using these estimates.

Sources

Last checked 5 October 2026.

Cite this page

Allmat, "Concrete steps and stairs calculator", https://allmat.com.au/concrete-calculator/steps, checked 5 October 2026.

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