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Stair Calculator

Estimate riser count, tread count, run, and angle for a simple straight stair layout.

Stair Calculator Inputs

Results computed instantly — your data never leaves your device.

Stair Calculator Results

Real-Time

Risers / treads

172 / 171

Actual riser height

6.98 in

Total horizontal run

1710.00 in

Stair angle

34.90°

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How to Use the Stair Calculator

  1. 1

    Enter total vertical rise in inches.

  2. 2

    Enter target riser height.

  3. 3

    Enter tread depth.

  4. 4

    Review riser count, actual riser, total run, and angle, then verify local building requirements.

Formula & Mathematical Basis

Risers = ceil(total rise ÷ target riser); actual riser = total rise ÷ risers; treads = risers − 1; run = treads × tread depth; angle = atan(actual riser ÷ tread depth).

Variable Key

rise

Total vertical rise in inches

riser

Target vertical height per step

tread

Horizontal depth per tread

📝 This is a layout estimate; landings, nosings, headroom, handrails, and jurisdictional code requirements are not modeled.

Step-by-Step Examples

1

Straight stair layout

Scenario: 120 inches total rise, 7-inch target riser, 10-inch tread.

  1. 1.Divide 120 by 7 and round up to 18 risers.
  2. 2.Calculate actual riser as 120 ÷ 18.
  3. 3.Use 17 treads for a straight stair.
  4. 4.Multiply 17 by 10 inches for the run.
✅ The estimate is 18 risers, 17 treads, 116.67 inches run, and approximately 36.53°.

Practical Use Cases

  • Create an early stair layout estimate.
  • Compare rise/run assumptions before detailed design.

Common Pitfalls

  • Using total rise as the riser height.
  • Forgetting that a straight stair often has one fewer tread than risers.
  • Skipping code and structural review.

Frequently Asked Questions

Is this a permit-ready design?

No; verify local code, structure, headroom, landings, and safety requirements.

Does it include a landing?

No; it models a simple straight run.

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