Stair Calculator | Risers, Treads & Angle

Stair Calculator

Quickly compute riser count, riser height, tread depth, total run and stair angle. Supports both metric and imperial units and uses the standard step rule 2R + T ≈ 25.5 in (≈65 cm).

Units

Total rise (floor-to-floor)

Preferred riser

Enter total vertical height between floors (in inches for imperial, cm for metric).

Preferred riser height (common: 6.5–7.5 in / 16.5–19 cm). Leave blank to auto-select.

Step comfort rule constant

Rule: 2×Riser + Tread ≈ constant. Default 25.5 inches (≈65 cm). Adjust if you follow a different guideline.

Riser limits (min / max)

Common imperial range shown. When you switch to metric these values update automatically.

Quick references

Rule	2R + T ≈ constant
Default constant	25.5 in (≈65 cm)
Comfort riser	6.5–7.5 in (16.5–19 cm)
Comfort tread	10–11 in (25–28 cm)

How the calculator chooses values

It divides the total rise into an integer number of risers so the resulting riser height falls inside your min/max limits. Then it computes tread depth from the comfort rule. If a preferred riser is given the tool tries to honor it and adjusts to best fit.

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What is a Stair Calculator?

A Stair Calculator is a practical online tool that helps you design and plan stairs safely and accurately. By entering basic measurements — like total rise, step height, tread depth, and number of steps — you can instantly calculate the ideal stair dimensions that meet building code requirements.

Whether you’re a homeowner building a new staircase or a contractor planning a renovation, this tool ensures your stairs are comfortable, safe, and perfectly proportioned.

Why Use a Stair Calculator?

Building stairs manually involves tricky math and precision. The Stair Calculator simplifies the process by automatically computing all essential stair parameters, helping you:

Determine the number of steps needed for your total height.
Find accurate riser height and tread depth for comfort and safety.
Ensure your design meets building code standards.
Visualize and plan stairs for wood, concrete, or metal structures.

It’s ideal for architects, builders, DIY enthusiasts, and homeowners who want precise results before cutting materials or pouring concrete.

How It Works

Enter the total rise (the vertical distance between floors).
Set the preferred riser height (usually 7 to 7.5 inches).
The calculator will automatically compute the number of steps and tread length.
Optional inputs, like stair angle, run, or nosing length, help refine your design further.
Get instant results that can be printed or used for blueprint drawings.

Example:
If your total rise is 105 inches and you want a riser height of 7 inches, the calculator will show that you need 15 steps with a comfortable tread depth for safe walking.

Tips for Perfect Stairs

Keep riser height between 6.5–7.5 inches for safety.
Tread depth should be 10–11 inches for comfort.
Add a small nosing (1 inch) for smoother step transitions.
Always double-check results with local building codes before construction.

Final Thought

A Stair Calculator makes stair planning simple, safe, and precise. It eliminates guesswork, saves time, and ensures every step is built to perfection. Whether it’s for your home, office, or outdoor project, use this calculator to design stairs that are both functional and elegant.