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Calculators & guides

Concrete Steps Calculator

Estimate solid concrete steps from the number of risers, regular tread depth, rise, width and a full-height top platform.

Units

Geometry dimensions — schematic, not to scaleT (run)P (platform)n × RRW = stair width
Schematic · not to scale · quantity repeats the entire solid

Full-height solid platform; 0 for none.

Concrete & bag assumptions

Density is the placed concrete density, not dry bag weight. Defaults are examples for normal-weight concrete. Bag weight does not determine yield; use the mixed yield printed on your product.

Estimate cost (optional · USD)

All cost fields are optional and user-entered. Ready-mix and bags are alternatives, never added together. No average or local prices are assumed — use a real quote. Labor per area is available only for shapes with a defined footprint.

Formula & solid model

V = W × R × [T × n(n − 1)/2 + P × n] × Q

All lengths convert to metres before calculation. Blank waste = 0%. Zero dimensions or quantity produce zero volume. Display values are rounded; costs and bags use unrounded volumes.

n risers, n − 1 treads of depth T, then platform P at height n × R. Solid down to level grade, not a suspended or sloped stair slab. Sum of tread prisms: W × T × R × (1 + … + n − 1). Platform: W × P × n × R.

Stairs · incl. 10% waste

You need approximately 0.871 cubic yards

23.528 ft³ · 0.666 m³ · 666.23 litres

Volume

UnitExact+10% waste
Cubic yards0.7920.871
Cubic feet21.38923.528
Cubic metres0.6060.666
Litres605.666666.232

Placed weight · incl. waste

3,529.17 lb / 1,600.8 kg

Density: 150 lb/ft³ · weight = volume × density

Selected premix bags · incl. waste

40 × 80 lb bags

Yield: 0.6 ft³ / bag · total volume ÷ yield, rounded up.

Estimate inputs & formula

Number of risers (n): 4 · Rise (step height): 7 in · Run (tread depth): 11 in · Stair width (W): 4 ft · Top platform depth (P): 11 in · Quantity (Q): 1

V = W × R × [T × n(n − 1)/2 + P × n] × Q

n − 1 regular treads + full-height platform; solid down to level grade.

Estimate only, not engineering advice. Actual needs vary with subgrade, forms and spillage. Confirm final quantities and product yields with your supplier or contractor before ordering.

What this calculates

With n risers, there are n − 1 regular treads, followed by the top platform. Each tread prism has height i × rise, for i = 1 through n − 1. The platform is solid down to level grade at height n × rise. This is not a suspended or sloped stair slab.

Formula

V = width × rise × [run × n(n − 1)/2 + platform depth × n] × quantity; n = risers

Worked example

4 risers, 7 in rise, 11 in run, 4 ft wide, 3 ft top platform

  1. 1.3 regular treads: 4 × (7/12) × (11/12) × 6 = 12.83 cu ft
  2. 2.Full-height platform: 4 × 3 × (4 × 7/12) = 28 cu ft
  3. 3.Total: 40.83 cu ft = 1.512 cu yd; with 10% waste ≈ 1.664 cu yd

Common mistakes

  • Counting the top platform as another regular tread, or counting it twice. Its depth is entered separately and it is included at full stair height.
  • Using inconsistent rise or run; most codes require uniform steps.

Frequently asked questions

Does this include a landing?

Yes, the entered top platform depth is included as a full-height solid prism. Set it to 0 for no platform. If your landing is a thin slab rather than solid down to grade, calculate that slab separately instead.

What rise and run should I use?

Residential codes commonly limit rise and set a minimum tread depth. Check your local code before forming.