Concrete Stairs Calculator
Solid poured steps. Pick porch, entry, or garden, then enter width, rise, and run.
This flight is about a cubic yard or more. A ready-mix truck is usually easier than mixing that many bags by hand.
How the numbers are figured
Solid stairs sitting on grade are stacked rectangles. The first step is one riser tall. The next is two risers tall, and so on. That adds up to width × rise × run × N × (N + 1) ÷ 2, with rise and run converted from inches to feet. Divide cubic feet by 27 for cubic yards. Bags use standard US pre-mix yields and round up.
This is for a solid pour, not a thin slab over dirt fill. A landing is a separate rectangle — add it with the slab calculator.
Common questions
How do you calculate concrete for stairs?
Treat solid poured stairs as stacked blocks. Volume is width times rise times run times N times (N + 1) divided by 2. Convert inches to feet first. Divide cubic feet by 27 for cubic yards.
How many 80 lb bags for 3 porch steps?
Three steps that are 3 feet wide with a 7.5 inch rise and an 11 inch run take about 10.3 cubic feet. With 10% extra, plan on 19 bags of 80 lb mix.
Does this include a landing?
No. A landing is a flat rectangle. Figure the steps here, then use the slab calculator for the landing and add the two results.