Calculation of stairs
Selecting the ideal height and depth of steps
to see the ideal parameters
Ladder calculator
📏 Formula for an ideal staircase (Blondel Method)
For a staircase to be safe and comfortable, it must comply with the biomechanics of the human step. Architect François Blondel developed the “Golden Formula” back in the 17th century.
2H + S = 60...64 cm
- H - height of the step (riser).
- S - width of the step (tread).
- 60-64 cm is the average human step length.
💡 Calculation example: If the height of the step is 17 cm, then the width should be:
63 - (2 × 17) = 29 cm. These are the parameters of an ideal staircase.
Table of norms: Convenient or Dangerous?
Not all sizes are acceptable. Building codes (SNiP) dictate strict safety frameworks. Check your calculations with this table:
| Parameter | ✅ Ideal (Comfort) | ⚠️ Acceptable | ⛔ Dangerous / Inconvenient |
|---|---|---|---|
| Tilt angle | 30° - 37° | 20° - 45° | > 45° (Steep) |
| Step height (H) | 15 - 17 cm | 14 - 20 cm | > 20 cm |
| Step width (S) | 27 - 30 cm | 25 - 32 cm | < 25 cm |
🏗 Builder's Dictionary: What do you think?
In order not to get confused in the drawings, it is important to understand the terminology of structural elements.
- Stringer: A supporting beam under the steps (resembling a sawtooth) on which the steps are laid on top. The most popular option for wooden stairs.
- String: Supporting beam to the side of the steps. The steps are inserted into grooves inside this beam.
- Tread:The horizontal plane of the step where you place your foot.
- Riser: Vertical part (height). “Open” stairs may not have risers.
- Clearance: The distance from any step to the ceiling (floor) above your head. There should be a minimum of 200 cmso that a tall person does not hit his head when descending.
Types of stairs: Which one to choose?
The choice depends on the available space in the house. Our calculator will help calculate the main types:
- Direct (Marching): The simplest and safest, but requires a lot of space in length.
- L-shaped (90° rotation): Saves space, installed in a corner. The turn is realized through the platform (more convenient) or winder steps (more compact).
- U-shaped (180° rotation):A compact “mine” where the marches go in opposite directions.
- Screw: Takes up minimal space, but is inconvenient for frequent walking and lifting furniture. Recommended as an auxiliary only.
Frequently asked questions (FAQ)
🔹 How many steps should there be in one flight?
It is recommended to make an odd number of steps (to start and end the movement with one leg), but no more than 15-18 pieces in one flight. If you need to go higher, be sure to make an intermediate resting area.
🔹 What is the minimum opening needed for the stairs?
Depends on the steepness, but the “golden rule” of safety: the opening should be such that when lifting, the distance from the top of the head to the edge of the ceiling is at least 200 cm. A smaller distance is dangerous.
🔹 What to do if the stairs are too steep?
You have three options:
1) Increase length of the opening.
2) Change the type of construction to L-shaped (with a turn) or add winder steps.
3) Use steps of the “Goose Step” type (variable width), but this is a compromise of convenience.