Stair Calculator
Calculate stair dimensions including rise, run, number of steps, and total length for safe and comfortable staircase construction.
Stair Calculation Results
Detailed Measurements:
Code Compliance Check:
About
Our Stair Calculator helps builders, architects, and DIY enthusiasts design safe and comfortable staircases that meet building codes and ergonomic standards.
Why Choose
Accurate stair calculations, building code compliance checks, visual representation, and multiple stair types for different space requirements and comfort levels.
Features
Calculate number of steps, rise per step, total run, stringer length, and verify code compliance using the standard 2R + T = 24-25 inch formula.
Benefits
Design safe staircases, ensure building code compliance, optimize space usage, and create comfortable stairs that reduce fatigue and improve safety.
Enter Dimensions
Input your total height, desired rise per step, and tread depth. Use typical values of 7-8″ rise and 10-11″ tread depth.
Choose Stair Type
Select standard, compact, or comfortable stairs based on your space constraints and usage requirements.
Get Results
View detailed calculations with visual representation, code compliance check, and all measurements needed for construction.
Frequently Asked Questions – Stair Calculator
The 2R + T rule states that twice the rise plus the tread should equal 24-25 inches (2 × Rise + Tread = 24-25″). This formula ensures comfortable and safe stairs. For example, a 7.5″ rise with 10″ tread gives 2(7.5) + 10 = 25″, which is ideal for most people’s walking rhythm.
Most building codes require: maximum rise of 7.75″ (some allow 8″), minimum tread depth of 10″, maximum variation of 3/8″ between steps, minimum headroom of 6’8″, and handrails for stairs with 4+ risers. Always check local building codes as requirements may vary by location.
Measure from the finished floor of the lower level to the finished floor of the upper level. Include all flooring materials (hardwood, carpet, tile, etc.) in your measurement. Don’t measure to subflooring – the total height should be the actual vertical distance people will climb.
Rise is the vertical height of each step (typically 7-8 inches), while run refers to the horizontal depth of the tread where you step (typically 10-11 inches). Total rise is the complete vertical height, and total run is the horizontal distance the stairs cover.
Stringer length is calculated using the Pythagorean theorem: √(total rise² + total run²). This gives you the diagonal length of the stair stringer. Add extra length for cuts and connections. For example, with 90″ rise and 110″ run: √(90² + 110²) = 142.1 inches.