Concrete Stairs Calculator

1. Enter the number of steps in the flight.
2. Enter the rise and run of one step in inches, and the stair width.
3. Add a top landing depth if the flight ends in a solid landing, and a 10 percent waste allowance.
4. Pick a bag size for a bag count, then read the cubic yards to order.

Here is what each result line means:

A concrete stairs calculator turns the size of a flight of steps into the amount of concrete to order. It is built for solid, cast-in-place steps, the kind poured for a porch, a deck landing or an entry, where the concrete fills a stepped form down to the base.

Because each step is poured on top of the ones below it, a staircase uses far more concrete than its surface suggests. The tool adds up that stacked volume, converts it to cubic yards and bags and adds a waste allowance. To get the mix proportions right use the concrete mix calculator, and for the binder use the cement calculator.

Think of a solid flight as a stack of blocks: the top step is one block, the step below is two blocks tall, the next three, and so on. Adding those up gives the triangular number n times (n plus one) over two, which is why a tall flight grows so quickly.

1. Convert the rise, run and width from inches to feet by dividing by 12.
2. Multiply width by run by rise, then by n times (n plus one) over two, for the stepped volume in cubic feet.
3. Add a top landing if there is one, taken as a solid block the full flight height.
4. Add the waste allowance, divide by 27 for cubic yards and by the bag yield for a bag count.

For the footing the steps bear on, size it with the concrete bag calculator for a small pad.

Suppose you are pouring a porch flight of 5 steps, each 7 inch rise and 11 inch run, 36 inches wide, with no landing and 10 percent waste.

Calculation: in feet the rise is 0.583, the run 0.917 and the width 3. The step factor is 5 x 6 / 2 = 15. Volume = 3 x 0.917 x 0.583 x 15 = 24.06 cu ft, or about 0.89 cu yd. Adding 10 percent waste gives 26.47 cu ft, about 0.98 cu yd and roughly 45 eighty-pound bags.

The lesson: five modest steps already approach a cubic yard, because every step is solid to the base.

Number of Steps

Steps add up as a triangular number, so each extra step adds more than the last. A tall flight uses far more concrete than a short one of the same step size.

Rise and Run

Both scale the volume directly. A deeper tread or a taller riser lifts the whole stack, so small changes in step geometry move the total.

Width

Width multiplies everything, so a wide entry stair uses proportionally more than a narrow one.

Landings and Cheeks

A solid top landing, or thick side walls, add concrete beyond the steps. Include the landing depth, and work out any side cheeks separately.

There is more than one way to build concrete stairs, and they use different amounts of concrete.

This tool sizes the solid-steps case. For a suspended waist-slab flight, the concrete comes from the slab geometry an engineer sets, and the concrete cost calculator in the related tools can then price the pour.

Ordering Concrete for Steps

Size the flight in cubic yards and add waste before you order, so you can pour the whole flight without a cold joint between steps.

Pricing a Bag Job for a Few Steps

For a small porch flight, the bag count shows how many bags to buy and whether hand mixing is realistic.

Fitting the Flight to the Opening

The overall rise and run tell you how tall and how far the flight reaches, so it lands where you need it.

1. Sizing Only the Surface

Steps are solid, not a thin tread, so estimating from the surface area badly under-orders. The stacked volume is what fills the form.

2. Mixing Up Rise and Run Units

Enter the rise and run in inches and the width in inches too; the tool converts to feet. Swapping inches and feet throws the volume off.

3. Forgetting the Landing

A solid top landing can be a large share of the pour. Include its depth so you do not run short at the top.

4. Ignoring Side Walls

Formed steps often have solid side cheeks that hold extra concrete. Work those out separately and add them.

5. Treating the Estimate as a Code Check

Volume is not geometry compliance. Rise, run and landing limits come from your building code, not from this tool.

The arithmetic is exact for a solid flight; the usefulness depends on the step sizes, width and landing you enter.

Multiply the width by the run by the rise, then by n times (n plus one) over two, where n is the number of steps, because each step is solid on the ones below. Five 36 inch steps at 7 inch rise and 11 inch run are about 24 cubic feet, or roughly 0.98 cubic yards with waste.

Five solid steps 36 inches wide at a 7 inch rise and 11 inch run work out to about 24 cubic feet, or 0.89 cubic yards, before waste, and roughly 0.98 cubic yards with a 10 percent allowance. That is about 45 eighty-pound bags. Enter your own step sizes above.

Because solid steps are poured on top of one another, the volume grows as a triangular number, not with the surface. The bottom step carries the full stack above it, so even a short flight approaches a cubic yard of concrete.

Yes, if the flight ends in a solid landing. Enter the landing depth and the tool adds it as a solid block at the full flight height. Leave it at zero if the steps simply meet an existing floor or slab.

Step rise is commonly 6 to 7.75 inches and run 10 to 11 inches, but your local building code sets the limits. This tool uses whatever rise and run you enter to work out the volume; it does not check code compliance.

It depends on the flight and bag size. A five-step porch at 36 inches wide is about 45 eighty-pound bags with waste, which is a lot to mix by hand. The tool gives the bag count for your steps and bag size, rounded up.

Yes, about 10 percent. Formed steps lose concrete to the forms, an uneven base and finishing, and a cold joint between steps is hard to avoid if you run short, so a margin matters.

No. It sizes solid steps filled to the base. A waist-slab or suspended flight has an open underside and uses less concrete, sized from the slab geometry an engineer provides.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• QUIKRETE Concrete Mix 1101 data sheet (QUIKRETE; bag yields 0.60, 0.45 and 0.30 cu ft).
• National Ready Mixed Concrete Association (NRMCA; ready-mixed concrete and ordering).
• American Cement Association (American Cement Association; concrete basics).