Concrete stairs calculator
For solid poured steps at a porch, stoop or back door. Enter the number of steps, the rise and run of each step and the width of the stair, and the calculator adds up every step down to the ground.
Calculator
Your estimate
Enter your measurements and select Calculate to see how much to order.
- Concrete to order
- cu yd
- Exact volume
- cu yd / cu ft
- Bags of 80 lb mix
- Cost with bags
- Cost with ready-mix
- Best way to buy
How it is calculated: length × width × thickness in feet gives cubic feet. Divide by 27 for cubic yards, then add your extra for waste and round up to the next quarter yard.
How the stairs calculator works
Solid poured steps are a stack of blocks. The bottom step is one riser tall and one run deep. The step above it sits on top and is also one run deep, but the concrete under it is two risers tall, and so on. Counting from the top, step n is a block of width × run × (rise × n). Adding every step from 1 to N gives the series 1 + 2 + … + N, which equals N(N+1) ÷ 2.
Volume = width × run × rise × N(N+1) ÷ 2
A landing at the top is a block as wide as the stair, as deep as the platform, and as tall as the full stair:
Platform volume = width × platform depth × rise × N
The calculator converts rise, run and platform from inches to feet, adds the two volumes, applies your waste allowance, and converts to cubic yards and bags.
Worked example
Three steps, each 7 in rise and 11 in run, 4 ft wide, with a 24 in platform at the top:
- One block: 4 × (11 ÷ 12) × (7 ÷ 12) = 4 × 0.9167 × 0.5833 = 2.139 cu ft
- Steps: 2.139 × (3 × 4 ÷ 2) = 2.139 × 6 = 12.83 cu ft
- Platform: 4 × (24 ÷ 12) × (7 ÷ 12) × 3 = 4 × 2 × 0.5833 × 3 = 14.00 cu ft
- Total: 26.83 cu ft = 0.99 cu yd. With 10% waste, 29.52 cu ft, so order 1.25 cu yd or buy 50 bags of 80 lb mix.
What to enter
- Number of steps. Count the risers from the ground to the top surface. A stoop with three treads and a landing has three risers plus the landing, which you enter as the platform.
- Rise. The height of one step. Keep every riser the same height; codes commonly limit the variation between risers to a fraction of an inch.
- Run. The depth of one tread, nosing excluded.
- Width. The side-to-side width of the steps in feet.
- Platform depth. How far the top landing extends beyond a normal tread. For steps that end at a door with no landing, leave 0.
Limitations
- The formula assumes solid steps on flat ground. Steps built against a slope, or on top of a footing, need the footing added separately.
- Hollow-back steps, which have fill or a void underneath, use far less concrete. Precast and formed-with-void designs are not covered.
- Steps that wrap a corner or have curved treads need to be split into pieces.
- Rise and run affect safety and are set by building codes. This calculator estimates material only.
Frequently asked questions
How much concrete do I need for 3 steps?
For three steps 7 in high, 11 in deep and 4 ft wide with no landing, you need 12.8 cu ft, which is 0.48 cu yd. With 10% waste that is 14.1 cu ft, or 24 bags of 80 lb mix. Add a landing and the total roughly doubles.
Why does a landing add so much concrete?
Because the landing is as tall as the whole stair. A 2 ft landing on a three-step stair is a solid block 2 ft deep and 21 in tall across the full width, which is more than all three steps combined.
Should I use bags or a truck for steps?
Most porch steps are under a cubic yard, so bags are practical, especially since steps are poured from the bottom up and bags let you pace the work. For a wide stair with a landing, price a short load too.