Staircase Calculator – Work Out Rise, Run, and Angle with Ease

Designing or building a staircase isn’t guesswork — it’s about balance, comfort, and safety. If the risers (vertical parts) are too high, climbing feels steep and tiring. If the treads (horizontal steps) are too shallow, walking feels awkward or even unsafe. That’s where a Staircase Calculator comes in. It helps you determine the perfect number of steps, riser height, tread depth, angle, and even the stringer length, all based on your project’s dimensions.

Why Use a Staircase Calculator?

• Safety first: Building codes usually specify maximum riser height and minimum tread depth.
  
• Comfort: Properly calculated stairs feel natural to walk on.
  
• Accuracy: Instead of rough estimates, you get exact measurements tailored to your rise and run.
  
• Efficiency: Save time by letting the tool do the math for you.
  

What You Enter in the Calculator

To get accurate results, you’ll provide a few key details:

• Total Rise (mm): The vertical distance from the lower floor to the upper floor.
  
• Total Run (mm): The horizontal span the staircase will cover.
  
• Stair Width (mm): The overall width of the stairs (important for design and space planning).
  
• Maximum Riser Height (mm): The tallest allowed height for each step (for safety and comfort).
  
• Minimum Tread Depth (mm): The shallowest acceptable tread depth (so your foot lands comfortably).
  

Results You’ll Get

Once you’ve entered the details, the calculator shows:

• Number of Steps: How many steps are needed.
  
• Riser Height: The exact height of each step.
  
• Tread Depth: The usable depth of each step.
  
• Stair Angle: The angle of the staircase (steeper vs. gentler slope).
  
• Stringer Length: The diagonal board length that supports the steps.
  

How the Calculator Works (Step by Step)

1. Divide the total rise by your chosen maximum riser height. This gives the ideal number of steps (rounded to the nearest whole number).
   
2. Recalculate the riser height by dividing the total rise by that step count — ensuring every riser is consistent.
   
3. Calculate tread depth by dividing the total run by the number of treads (number of steps minus one).
   
4. Find the stair angle using trigonometry: angle = arctan(total rise ÷ total run).
   
5. Measure stringer length using the Pythagorean theorem: √(rise² + run²).
   

Example

Suppose your total rise is 2800 mm, your total run is 3500 mm, and the maximum riser height is 190 mm.

• Total rise ÷ max riser height = 2800 ÷ 190 = 14.7 → round to 15 steps.
  
• Riser height = 2800 ÷ 15 ≈ 187 mm.
  
• Tread depth = 3500 ÷ 14 ≈ 250 mm.
  
• Angle = arctan(2800 ÷ 3500) ≈ 38.7°.
  
• Stringer length = √(2800² + 3500²) ≈ 4507 mm.
  

Result: 15 steps, 187 mm risers, 250 mm treads, 38.7° angle, 4507 mm stringer.