Concrete Steps Calculator
Works out the concrete for solid poured steps sitting on the ground. Enter the rise, the going and how many steps, and it accounts for the way each step sits on the ones below it.
Includes the waste allowance — this is the figure to order.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
volume = rise × going × width × n(n+1)/2 × (1 + waste)
Solid steps poured on the ground are not n identical blocks — each step sits on top of everything below it, so the stack is the triangular number 1+2+…+n. Four steps is ten blocks, not four. This is the single biggest source of under-ordering on step pours.
What to watch out for
Steps are the concrete shape people most often get wrong:
- The volume is triangular, not linear. Doubling the number of steps roughly triples the concrete. Four steps take ten step-blocks; eight steps take thirty-six.
- Every riser must be identical. Building regulations everywhere require it, and a single odd step is a genuine trip hazard. Divide the total height by a whole number of risers.
- Rise and going are related. A common rule is 2 × rise + going ≈ 630 mm. A 170 mm rise pairs with a 290 mm going.
- This assumes solid steps. Steps formed over a void, or cast on a supporting waist slab, use considerably less — this calculator will overstate those.
Frequently Asked Questions
How much concrete for 4 steps?
At 170 mm rise, 280 mm going and 1.2 m wide, four solid steps need about 0.57 m³ before waste — roughly 0.63 m³ ordered, or 51 × 25 kg bags.
Why is the volume not just steps × step size?
Because solid steps sit on top of each other. The top step is one block high, the one below it two, and so on. Four steps is 1+2+3+4 = 10 blocks of concrete, not 4.
What is a comfortable step rise?
150–190 mm (6–7.5 in), with every riser identical. Pair it with a 250–300 mm going; the usual check is that twice the rise plus the going comes to about 630 mm.
Can I save concrete by filling the middle?
Yes — hardcore or rubble fill inside the form is common on larger flights, with a 100–150 mm concrete skin over it. That is a different calculation; this one assumes fully solid steps.