Design your staircase with accurate step counts, stringer lengths, and material estimates.
Our stair calculator helps you design a safe, code-compliant staircase by calculating the exact number of steps, stringer dimensions, and material costs. Whether you're building new stairs or replacing an existing staircase, accurate measurements are essential for safety and code compliance.
For example, a 105-inch total rise with 7-inch risers yields exactly 15 steps. With 10-inch treads, the total run is 140 inches (11 ft 8 in). Stringer length would be approximately 175 inches (14 ft 7 in), and you'd need 3 stringers for a 3-ft wide staircase.
Most residential building codes (IRC) require: maximum riser height of 7.75 inches, minimum tread depth of 10 inches, all risers within 3/8 inch of each other, minimum stair width of 36 inches, and handrails on at least one side. Always check your local code before starting construction.
Your choice of stair materials affects both cost and appearance. Here's what to expect:
| Material | Cost per Step | Pros | Cons | Best For |
|---|---|---|---|---|
| Basic (Pine / MDF) | $30-50 | Affordable, paintable, easy to work with | Less durable, can dent easily | Budget projects, utility stairs, basements |
| Premium (Oak / Hardwood) | $80-150 | Durable, beautiful grain, adds home value | Expensive, requires staining/finishing | Main staircases, entryways |
| Carpet Runner | $40-70 | Soft underfoot, reduces noise, non-slip | Shows wear, traps dust, needs replacement | High-traffic family stairs, homes with kids/elderly |
The standard stair riser height is 7 inches. Building codes typically allow a range of 4 to 7.75 inches. All risers in a single staircase must be within 3/8 inch of each other to comply with building codes. Consistency is critical for safety.
Stringer length is calculated using the Pythagorean theorem (a² + b² = c²). The total rise is one leg (a), the total run is the other (b), and the stringer length is the hypotenuse (c). Our calculator does this automatically — simply input your total rise and desired riser/tread dimensions.
For stairs up to 36 inches wide, you need at least 3 stringers (one on each side and one in the center). For stairs 36-48 inches wide, use 4 stringers. Stringers should be spaced no more than 18 inches apart and are typically cut from 2x12 lumber.
Open riser stairs have no vertical board between treads, creating a modern, open look. Closed riser stairs have a riser board between each tread and are more traditional. Open risers can feel less cluttered but may not meet code in all jurisdictions.
Most jurisdictions require a building permit for new stair construction or significant staircase modifications. Permit requirements vary, but stairs are considered a critical safety element. Always check with your local building department before starting construction.
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