Concrete
Concrete Steps Calculator
Enter the step width, count, rise and tread. This uses the real staircase volume, not one block per step.
Over-excavation, spillage and uneven subgrade. 5-10% for formed work, 10-15% on rough ground.
Yields are the figures printed on the bag. Speciality mixes differ — check yours.
Optional. Leave at zero to skip the cost estimate.
Material quantity estimate for planning and purchasing. Not structural engineering advice, not a bid, and not a code determination.
Why step volume is not steps × one block
This is the calculation most step calculators get wrong.
In a solid poured stair, the bottom step is one riser tall, the second is two risers tall, the third is three, and so on. The total is the triangular number of the rise, not a flat multiple:
volume = width × tread × rise × n(n+1)/2
Treating every step as a single rise-tall block undercounts by (n+1)/2 — which is 3× too little concrete at five steps and 5.5× too little at ten. Ordering a third of what you need is the kind of error you discover with the forms built and a truck idling in the driveway.
Rise and run limits
The IRC caps riser height at 7.75 inches and sets minimum tread depth at 10 inches for residential stairs, with no more than 3/8 inch variation between the tallest and shortest riser in a flight. Exterior steps are commonly built to a gentler 6-7 inch rise with an 11-12 inch tread.
To size a flight: measure the total rise from finished grade to the landing, divide by your target riser height, and round to a whole number of steps. Then divide the total rise by that count to get the actual riser height — all risers equal.
| Steps | Total rise | Volume | Cubic yards | 80 lb bags |
|---|---|---|---|---|
| 2 steps | 14 in | 6.4 ft³ | 0.24 yd³ | 11 |
| 3 steps | 21 in | 12.8 ft³ | 0.48 yd³ | 22 |
| 4 steps | 28 in | 21.4 ft³ | 0.79 yd³ | 36 |
| 5 steps | 35 in | 32.1 ft³ | 1.19 yd³ | 54 |
| 6 steps | 42 in | 44.9 ft³ | 1.66 yd³ | 75 |
| 7 steps | 49 in | 59.9 ft³ | 2.22 yd³ | 100 |
| 8 steps | 56 in | 77.0 ft³ | 2.85 yd³ | 129 |
Void the core and save half the concrete
Solid steps are rarely necessary. Standard practice on anything more than three steps is to build the form, backfill the interior with compacted crushed stone, and pour a 5-6 inch shell over it. You keep the bearing and the wear surface and cut the concrete volume by roughly 40-55% on a five-step flight.
This calculator gives you the solid volume, which is the safe number to order and the right starting point. If you are voiding the core, calculate the solid volume, then subtract the void: for a stepped fill, the void is roughly the solid volume less a 6 inch shell on the treads, risers and sides.
Steps also need reinforcement — #3 or #4 bar running the width and turned up into each riser — and they should be tied to the foundation or set on their own footing below frost depth so the flight does not heave away from the house.
Common questions
How much concrete for 5 steps?
A 4 ft wide flight of five steps at 7 in rise and 11 in tread is 32.1 cubic feet solid, or 1.19 cubic yards — about 54 bags at 80 lb. Add waste and order 1.35 yards, or half that if you are voiding the core with compacted gravel.
What is the maximum riser height for steps?
The IRC allows 7.75 inches maximum for residential stairs, with a minimum 10 inch tread and no more than 3/8 inch variation between risers in a flight. Exterior steps are usually built to 6-7 inches for comfort.
Can I fill the middle of concrete steps with gravel?
Yes, and it is normal practice above three steps. Backfill with compacted crushed stone and pour a 5-6 inch reinforced shell. It saves roughly 40-55% of the concrete on a five-step flight with no loss of capacity.