Enter each stair run
Use one group for identical runs. Add another group when dimensions or the number of steps change.
Concrete & masonry
Concrete Stairs Calculator
Estimate concrete for solid straight stair runs with equal tread depth and riser height. Combine multiple stair groups, add separate non-overlapping landings, apply a project allowance, and optionally estimate bags or ready-mix ordering quantities.
Quantity estimator only.Enter stair and landing dimensions from your plans, designer, engineer, contractor, or other appropriate project guidance. This calculator does not determine code-compliant tread or riser dimensions, structural reinforcement, waist-slab thickness, loads, foundations, handrails, or code compliance.
How to use the concrete stairs calculator
This calculator estimates the volume of solid straight concrete stairs formed as stacked rectangular layers. Enter the number of equal steps, overall stair width, tread depth, and riser height for each stair-run group. Optional landings are calculated separately as rectangular prisms.
Add separate landings
Include only additional landing volume that does not overlap the solid stair-run geometry.
Choose an allowance
Apply only the project allowance appropriate to your own estimating method, plans, and job conditions.
Plan the purchase
Optionally enter manufacturer bag yield or your supplier's ready-mix increment and price.
Concrete stair formulas
Solid stair runVolume = width × tread depth × riser height × n(n + 1) ÷ 2
Repeated identical stair runsGroup total = single-run volume × quantity
Separate rectangular landingLanding volume = width × length × thickness × quantity
Whole projectBase concrete = all stair-run volume + all landing volume
Planning volumeRequired = base concrete × (1 + allowance ÷ 100)
Bagged concreteBags to buy = ceiling(required volume ÷ manufacturer bag yield)
Concrete stairs example
A solid 4-step run that is 4 ft wide, with 11 in treads and 7 in risers, requires about 21.389 ft³ before allowance. With a 10% allowance, the requirement becomes about 23.528 ft³, or 0.871 yd³ and 0.666 m³. At a test product yield of 0.60 ft³ per bag, the project would round to 40 whole bags, purchasing 24 ft³ and leaving about 0.472 ft³ above the calculated requirement.
Concrete stairs calculator FAQs
What kind of stairs does this calculator model?
It models solid straight stair runs with equal tread depth and equal riser height. Each successive step contains one additional riser-height layer of concrete beneath it.
Can I include a landing?
Yes. Add a separate landing as a rectangular prism. Enter only additional landing concrete that does not overlap volume already counted in the stair run.
Can I calculate several stairways together?
Yes. Add multiple stair-run groups and use quantity for identical runs. The calculator combines exact volumes before allowance and purchasing.
Does it determine the number or size of steps I should build?
No. Step count, tread depth, riser height, reinforcement, structural dimensions, and code requirements must come from appropriate project plans or qualified guidance.
Does it work for suspended or waist-slab stairs?
No. Suspended, hollow, waist-slab, spiral, curved, winder, tapered, precast, or variable-step stairs require different geometry.
Why do I enter bag yield instead of bag weight?
Concrete yield varies by product. Enter the actual manufacturer-stated volume yield rather than assuming a universal yield from bag weight.
Why are bags rounded only once?
The calculator adds the exact whole-project requirement first and then rounds to whole bags. Rounding every stair or landing separately can overstate the purchase.
Can I use Metric units?
Yes. Stair width switches between feet and meters, while tread depth, riser height, and landing thickness switch between inches and centimeters. Landing width and length switch between feet and meters.
Can I save or share the calculation?
Yes. After a successful calculation, the project state is stored in the URL when it fits within a conservative URL-size limit.
Reference methodology
Unit conversions use the international-foot relationship of exactly 0.3048 meter. Stair geometry uses the arithmetic-series identity 1 + 2 + ... + n = n(n + 1) / 2. Bag calculations require user-entered product yield and round only the final project requirement to whole bags. Structural design decisions are intentionally outside this calculator's scope.
Assumptions and limitations
- Each stair-run group is a solid straight stepped mass with equal tread depth and equal riser height.
- The stair formula assumes the first tread has one riser-height layer, the second has two, and so on through step n.
- Landings are separate solid rectangular prisms and must not overlap concrete already represented by a stair run.
- The project must include at least one stair-run group; landing-only projects belong in a general concrete-volume calculator.
- The allowance percentage is user supplied and applied after exact stair and landing volumes are combined.
- Bag quantities depend on the manufacturer yield entered and round once at whole-project level.
- Ready-mix rounding occurs only when a supplier increment is entered.
- Cost includes only entered material price, not labor, delivery, pumping, forms, reinforcement, taxes, or fees.
- Suspended, hollow, waist-slab, spiral, curved, winder, tapered, precast, and variable-step stairs are outside this model.
- This tool estimates quantity only and does not validate structural adequacy, accessibility, stair safety, or code compliance.