There is one measurement that many people look for when planning a staircase – and another feature that is even more important for safety.
This measurement refers to the height of the stair riser. What actually determines whether a staircase feels safe to walk on, however, is how consistent the heights of all the steps are.
A staircase can have a comfortable riser height but still be unsafe if even a single step is out of place. That’s why the evenness of the steps must come first, before you determine which measurement is optimal.
Why is a consistent step height more important than an exact measurement?
Consistent step height is more important because a step that differs from the others disrupts your walking rhythm and increases the risk of tripping.
We often walk up stairs without looking at each step. After two or three steps, our foot has learned how high the next step is, and the rest of the movement happens almost automatically.
When one step differs from the others, your foot lands too high or too low. The difference doesn't have to be significant—a deviation of just a few centimetres can be enough to make the staircase feel unexpected.
What are the standard dimensions for indoor and outdoor steps?
As a general guideline, indoor stairs often have a riser height of 16–18 cm and a tread depth of at least 25 cm, while outdoor stairs often have riser heights of 13–16 cm and tread depths of 30–35 cm. When planning a staircase, the dimensions must also be adapted to the total height difference, the slope, and how the staircase will be used.
| Measurement or characteristic | What usually works | Comment |
|---|---|---|
| Indoor step height | 16–18 cm | Guidelines for a comfortable indoor staircase. The steps should be the same height throughout the staircase. |
| Indoor step depth | At least 25 cm | A standard starting point that should provide enough space for the foot to land steadily. |
| Outdoor step height | 13–16 cm | Lower steps result in a shallower staircase and can feel safer when the surface is slippery. |
| Outdoor step depth | 30–35 cm | Deeper steps are common in exterior staircases made of, for example, stone or concrete. |
| Indoor slope | 30–40 degrees | Steeper stairs require more effort and leave less room for your foot. |
| Gap between steps | Child-safe design | Öppningarna behöver utformas så att risken för att små barn faller igenom eller fastnar begränsas. |
How does the staircase formula for riser height and tread depth work?
The staircase formula states that twice the riser height plus the tread depth should be approximately 63 centimetres. This is a rule of thumb for comfortable proportions—not a regulatory requirement or a single “correct” measurement for all staircases.
The formula shows how height and depth need to be balanced. A taller step usually needs to be combined with a shallower step depth for the total to remain the same, but the result can still be a significantly steeper staircase.
- A more convenient ratio
- 2 × 17 cm + 29 cm = 63 cm
- A steeper ratio
- 2 × 20 cm + 23 cm = 63 cm
Both examples thus meet the rule of thumb, but the first one provides more room for the foot and a flatter step. Therefore, the formula must always be evaluated in conjunction with the staircase’s slope and intended use.
Can an outdoor staircase become uneven over time?
Yes. An exterior staircase that was level when it was built may, over time, develop one or more steps that are higher or lower than before.
Frost heave and ground movement can cause different parts of the substrate to rise or sink. The extent to which the stairs are affected depends, among other things, on their location, foundation, and soil conditions.
The result could be the most dangerous part of a staircase: a single step that has become higher or lower than the others.
Pay special attention to the bottom step
Feel free to measure your outdoor staircase after a few winters. The step that touches the ground is often the first to change when the ground shifts.
What are the regulations for balustrades and handrails on a staircase?
A handrail (staircase balustrade) needs to provide reliable support along the entire length of the staircase, while a stair rail (handrail) provides support when going up and down. The height, fixing, and design of the handrail need to be evaluated together. How the handrail (handrail)should be positioned on the staircasedepends on the staircase’s width, design, and intended use.
- Staircase balustrade
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The height and design of the railing must be adapted to drop height, the staircase’s location, and how it is used. Fixing must be able to withstand the loads to which the railing may be subjected, and the guardrail must follow the slope of the staircase without any unsafe gaps.
- Handrail
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The handrail should provide a firm and comfortable grip when you use the stairs. Handrails on both sides can provide extra support, especially on wide staircases or where many people use the stairs. The number of handrails and their placement need to be adapted to the staircase’s design and use.
What should you check when planning stair treads?
Start with the total elevation difference, and then make sure the steps are even, have a practical depth, and work well with the staircase’s slope, openings, and handrails.
Check these seven points
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Measure the total elevation difference
Measure from the finished floor or ground level at the bottom to the finished level at the top before determining the number of steps.
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Distribute the height evenly
Divide the total elevation difference so that all steps are the same height. Never place any remaining difference in the top or bottom step.
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Check the proportion using the step formula
Multiply the riser height by the tread depth twice. A result of about 63 centimetres is a common rule of thumb for a comfortable ratio.
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Exclude the projecting part of the stair tread
Estimate the depth of the step where your foot can actually land. The part that extends beyond the step below is not fully usable as a walking surface.
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Adapt your outdoor staircase to the weather and surface conditions
Outdoors, lower and deeper steps result in a shallower staircase and provide better footing when rain, snow, or ice make the steps slippery.
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Check the gap between the steps
Where young children may use the stairs, the openings between the treads must be designed to minimise the risk of children falling through or getting stuck.
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Plan handrail along with the staircase
Make sure the handrail provides stable and comfortable support when using the stairs. Handrails on both sides can provide extra safety, although the number and placement should be adjusted according to the width, design, and intended use of the stairs.
Always prioritise consistent step heights throughout the entire staircase. A single step that deviates from the norm can pose a greater risk of falling than a minor deviation from a recommended ideal measurement.
Should the staircase have a new railing or a handrail?
Tell us the dimensions of the staircase and whether it is indoors or outdoors, and our customer service team will help you find a made-to-measure balustrade or a handrail that fits the staircase's slope and design.
What are the most common questions about stair dimensions?
The most common questions concern how high and deep stair treads should be, how to use the stair formula, how uniform the treads should be, and what you need to consider when it comes to openings and handrails.
How high should a stair step be?
Indoors, a height of 16 to 18 centimetres is often used as a guideline for a comfortable staircase. This is a common guideline, not a measurement that applies to all staircases.
What is the staircase formula?
Twice the riser height plus the tread depth should be approximately 63 centimetres. This is a rule of thumb for comfortable walking, not a regulatory requirement.
How deep should the step be?
At least 25 centimetres indoors is a common guideline for ensuring there is enough room for the foot. Outdoors, 30 to 35 centimetres is typical.
Can the steps be different heights?
No, not in practice. An irregular step is a common cause of falls on stairs because it disrupts the walking rhythm that the foot has become accustomed to.
What are the specifications for the gap between the treads?
Where young children may use the stairs, the openings between the treads must be designed to minimise the risk of children falling through or getting stuck.
Is a handrail needed on both sides?
Handrails on both sides can provide extra support, especially on wide staircases. How many handrails are needed and where they should be placed depends on the staircase’s design and use.
Passar vajerräcke i en trappa?
Yes, a wire balustrade can be used, for example, in entrance steps. In areas where small children are present, keep in mind that horizontal wires can provide a foothold and increase the risk of climbing.
