How to Calculate an Internal Staircase: Formulas, Standard Measurements and Practical Advice

Do you want to know how to correctly calculate an internal staircase? In this article you will discover the essential formulas for designing an internal staircase, how to calculate rise, tread and number of steps, and what ideal measurements to respect.

Table of contents

• Why it is important to correctly calculate an internal staircase

• Basic formula for calculating a staircase: rise and tread

• How to calculate the number of steps in a staircase

• What are the ideal measurements for an efficient staircase

• Practical advice for designing your internal staircase

• Examples of Rintal staircases

• Need help designing your staircase? We can help you

Why it is important to correctly calculate an internal staircase

An internal staircase is not just a connection between two levels: it is a central architectural element that must combine aesthetics, functionality and safety. Precise design prevents structural errors and improves the daily user experience.
A well-calculated staircase:

• Improves the circulation of spaces and enhances the environment;
• Ensures a comfortable and regular ascent, reducing physical effort;
• Prevents structural inconveniences and ensures compliance with regulations

Neglecting these aspects means compromising comfort, safety and design. This is why it is essential to start with correct measurements and rely on professional solutions.

The basic formula for calculating a staircase: rise and tread

The relationship between rise (step height) and tread (step depth) is crucial for ensuring the stability and comfort of the staircase. To correctly calculate the dimensions of a staircase, there are several formulas. Below we present the most widespread formulas recognized as a reference in staircase calculation.

Blondel's formula

This is the most common rule for the ergonomic dimensioning of staircases.

Formula:

2 × rise + tread = 62 ~ 64 cm

• Rise = vertical height of a step (in cm)
• Tread = horizontal depth of a step (in cm)
• 62 ~ 64 cm = average length of human stride when climbing

The goal is to obtain a measurement compatible with the average length of the human stride, so as to make climbing natural and comfortable.

Example:

Imagine a rise of 18.5 cm. We want to understand which tread to pair to obtain a comfortable staircase.

We apply the formula:

2 × 18,5 + tread = 62 cm (we use 62 cm as the average value between 62 and 64)

37 + tread = 62

tread = 62 − 37 = 25 cm

Result:

• Rise: 18,5 cm
• Tread: 25 cm
• Verification: 2 × 18,5 + 25 = 62 cm, within the recommended range.
  
  

How to calculate the number of steps in a staircase

The number of steps in an internal staircase is obtained by dividing the total height difference between the two floors by the chosen rise.

Formula:
Number of steps = Total height ÷ Rise

Practical example:

• Height difference of 306 cm
  
• Chosen rise: 18 cm
  
• Calculation: 306 ÷ 18 = 17 rise (16 steps)

Once the number of steps is determined, it is possible to recalculate rise and tread to refine the project and obtain a proportionate staircase.

What are the ideal measurements for a comfortable staircase

Not all private staircases are the same. But there are standard parameters to follow to ensure a comfortable and safe ascent.

The optimal measurements are:

• Rise: between 17,5 and 19 cm
• Tread: between 20 and 25 cm
• Staircase width: at least 80 cm (better 90/100 cm for greater comfort). However, it is important to consider that not all design situations allow this parameter to be respected. In environments with limited space, it is possible to opt for space-saving staircases, where the staircase width is often less than 80 cm.
• Inclination: between 30° and 38°
• Parapet height: minimum 100 cm
• Handrail height: 100 cm from the step surface

For staircases compliant with regulations and suitable for daily use, it is always recommended to refer to the regulatory framework or ask for support from a professional.

Practical advice for designing your internal staircase

Every environment has its own requirements, and every internal staircase must be carefully designed to integrate perfectly into the available space, respecting functionality, aesthetics and safety.

Here are some things to consider:

• Available space: if you have limited space, the spiral staircase is a solution to keep in mind. For large environments, you can instead choose an open staircase, ideal for enhancing the design
• Materials: the choice between materials affects the aesthetic impact, resistance and maintenance of the staircase
• Style and intended use: consider whether it is a representative or service staircase. The requirements change, and so do the design solutions.

The correct combination of these elements will allow you to create a staircase that combines functionality and aesthetic value.

Examples of Rintal staircases: customized solutions for every design requirement

Every project requires the right solution. To help you identify the most suitable staircase for your space, here are three representative Rintal proposals of the main types: straight, spiral and space-saving. Different in structure and footprint, but united by construction quality and design

Composity straight staircase

Ideal for large spaces or open spaces, this open staircase stands out for its essential lines and modular structure. It can be made with staircase widths from 74 to 94 cm and configurations up to 16 steps (up to 17 rises), to serve floor-to-floor heights up to 416 cm, ideal for ensuring a comfortable and safe ascent. The steel structure and solid wood steps enhance every interior with minimal elegance

Discover more about the Composity open staircase

Phola spiral staircase

When space is limited but elegance remains a priority, opting for the Phola spiral staircase is the ideal choice. This is a modular spiral staircase that combines the natural charm of wood with the robustness of steel, for a solid and refined result. Available in different diameters, from 105 cm up to 180 cm, and in various finishes, the PHOLA spiral staircase fits easily into any residential context, offering customized solutions to make the most of every available centimeter without sacrificing design.

See all available solutions for the Phola spiral staircase.

Mini space-saving staircase

Mini is the space-saving staircase designed to optimize even the smallest environments.Thanks to the staggered and shaped steps, it allows for comfortable climbing while reducing footprint to a minimum. Made of beech wood, the steps are available in different color variants, to adapt consistently to any residential context.Suitable for lofts, attics and environments with limited dimensions, the MINI space-saving staircase offers a functional, safe and customizable solution, with an essential design and quality materials

Go to the page dedicated to the Mini-space saving staircase.

Need help designing your staircase? We can help you

Create the perfect staircase for your needs with our design service.

Relying on experienced professionals makes the difference. With the Rintal design service, you can count on customized solutions, designed to integrate perfectly into your space and satisfy every functional and aesthetic requirement.

Our designers support you step by step: from choosing the type to defining the measurements, up to selecting materials and finishes.