Concrete Steps Calculator

Enter the number of steps, riser height, tread depth, width and the depth of the landing at the top. The calculator works out the volume of a solid set of steps (no hollow core), converts it to bags or cubic yards, and flags risers or treads outside the IRC limits for house stairways.

Concrete steps calculator

How it works

Seen from the side, solid steps are a stack of rectangles. The first step is one riser tall, the second two risers tall, and so on. The landing at the top is as tall as all the risers together.

Side area = tread × riser × (1 + 2 + … + (n − 1)) + landing depth × n × riser
Volume = side area × width ÷ 1,728 → cubic feet
Bags = volume × (1 + extra %) ÷ bag yield (0.60 cu ft per 80 lb bag), rounded up

If you enter no landing, the top step is treated as an ordinary tread.

Worked example

Three 7 in risers with 11 in treads, 48 in wide, and a 36 in landing at the door:

Number of steps (risers): 3
Riser height: 7 in
Tread depth (run): 11 in
Step width: 48 in
Top landing depth: 36 in
Bag size: 80 lb bag (about 0.60 cu ft)
Extra for waste and spillage: 10%

The calculator gives:

Concrete volume: 27.42 cu ft (1.02 cu yd)
Bags of concrete: 51 bags (80 lb)
With 10% extra: 30.16 cu ft (1.12 cu yd)
Total rise: 1′ 9"
Total run including landing: 4′ 10"

The side profile is 11 × 7 + 11 × 14 + 36 × 21 = 987 sq in. Times 48 in of width, that is 47,376 cubic inches, or 27.42 cu ft (just over 1 cubic yard). At that size, ready-mix is usually easier than 50-plus bags.

Material and waste notes

Steps poured against an existing slab or over compacted fill use less concrete. Subtract any fill you place inside the forms.
The IRC limits for house stairways are a 7-3/4 in maximum riser and a 10 in minimum tread (R311.7.5). Your local code may treat exterior steps differently, so check before you set the forms.
Keep all risers the same height. The IRC allows no more than 3/8 in difference between the tallest and shortest riser in a flight.
The extra percentage is your allowance for form bulge and spillage, not a standard figure.

Frequently asked questions

How much concrete do I need for 3 steps?

For three 7 in risers with 11 in treads, 4 ft wide, with a 3 ft landing, about 27.4 cu ft (1.02 cu yd). Without a landing it is 12.8 cu ft.

What riser height should I use?

Divide the total height from the ground to the top surface by the number of steps, keeping each riser at or under 7-3/4 in if you follow the IRC limit for house stairs. The stair calculator on this site does that division for you.

Is it cheaper to use bags or ready-mix for steps?

That depends on local prices. As a rough guide, anything over about half a cubic yard is a lot of bag mixing (22-plus 80 lb bags), and many people switch to ready-mix or a mixer rental at that point.

Sources

Last reviewed: 25 September 2026. The calculation is covered by automated tests with known answers taken from the sources above. Found an error? Please let us know.