The calculation of stairs creates many doubts for many professionals. From the moment you understand the calculation procedure is very easy and you can calculate any ladder, regardless of its shape. Stairs are composed of the following elements:

Floor: is the horizontal surface where we step with our foot when we are climbing. They are also known as stair steps;

Mirror: is the vertical surface between one floor (step) and another. Where we hit with the tip of our foot when we climb;

Porch: is the horizontal surface more fulfilled than the floors (steps). They serve as rest when we climb and that overcomes a great height. Not every ladder has a threshold;
Bodyguard: is the vertical element along the stairs that serves as protection for people not falling from the stairs;

Handrail: This element is present in the stair guardrail and serves for people to support their hands when going up or down a ladder.
 
To calculate the comfort of stairs (when going up or down) we use the Blondel Formula which is a relation between the size of the floor and the stair mirror. The floor of an ordinary staircase varies from 25 cm to 30 cm and the mirror from 16 cm to 18 cm. Look at the formula and an example below:

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