Home Improvement

Stair Calculator

Calculate the number of steps and dimensions for your staircase.

Enter your total rise (floor-to-floor height) and desired tread depth to calculate the number of steps, exact riser height, and total horizontal run.

Floor-to-floor heightEnter a valid rise.

Number of Steps

—

Actual Riser Height

—

Total Run

—

How to Use This Tool

  1. Measure your total rise — the exact floor-to-floor height.
  2. Enter your target riser height (7-7.75" is typical and often code-compliant).
  3. Enter your tread depth, then calculate.

Stair Calculation Formulas

Number of Steps = Round(Total Rise ÷ Target Riser Height)

Actual Riser Height = Total Rise ÷ Number of Steps

Total Run = (Number of Steps − 1) × Tread Depth

Why the Actual Riser Differs From Your Target

Since the number of steps must be a whole number, this calculator rounds to the nearest whole step count, then recalculates the exact riser height needed to evenly divide your total rise — this is why the "actual" riser height is often slightly different from your initial target.

Why Run Uses (Steps − 1)

The top step is typically the floor/landing itself, so the horizontal run only needs treads for all steps except the final one — hence one fewer tread than the total step count.

Building Code Considerations

Most US residential building codes require riser heights between about 4 and 7.75 inches, with limited variance (often under 3/8") between the tallest and shortest riser in a single flight. Always verify your local building code requirements before finalizing stair dimensions.

Frequently Asked Questions

What is a comfortable riser height?

Most residential stairs use a riser height between 7 and 7.75 inches, which is generally comfortable and commonly compliant with US building codes — though exact requirements vary by jurisdiction.

Why does the run calculation use one fewer tread than steps?

The topmost "step" is typically the landing or floor surface itself, which doesn't need its own tread — so the horizontal run only accounts for treads on all steps below the top landing.

This calculator is provided for general informational and estimation purposes only. Results should not be treated as professional financial, tax, legal, medical, or engineering advice. Always verify critical calculations with a qualified professional or official source before making decisions.