Getting your stair tread dimensions wrong is one of the most common — and most expensive — mistakes in a staircase project. A tread that’s too shallow makes people feel unstable; one that’s too thick changes the riser height and throws off every other step in the run. Before you order, it helps to know exactly what each measurement means, what your local building code requires, and what shape your staircase actually needs.
This guide covers the three core measurements, code minimums for residential and commercial stairs, the ergonomic formula most designers use, common stair shapes, and how to measure before ordering.
The Three Core Stair Tread Dimensions
Every stair tread has three dimensions that matter for both safety and fit.
Depth (Run) Depth is the front-to-back distance your foot lands on — the horizontal surface you step onto. This is the most safety-critical measurement: too shallow and there isn’t enough surface for a full footstep, particularly going downstairs.
Épaisseur Thickness is how tall the tread board itself is. This affects the finished riser height of each step, so getting it wrong throws off the entire staircase geometry. It also determines how many times the tread can be sanded and refinished over its lifetime.
Length (Width) Length runs side to side across the staircase. On a standard enclosed staircase this equals the distance between walls; on an open-sided staircase it runs to the edge of the structure.
Code Minimums: Residential vs. Commercial
Building codes set the floor, not the ideal. Comfortable stairs are usually larger than the minimum.
Residential Stairs (IRC / IBC Standard)
| Dimension | Code Minimum | Comfortable Range |
|---|---|---|
| Tread depth | 254 mm (10 in) | 280–330 mm (11–13 in) |
| Riser height | Max 197 mm (7¾ in) | 165–180 mm (6½–7 in) |
| Stair width | 914 mm (36 in) min | 914–1,200 mm (36–48 in) |
| Nosing projection | 19–32 mm (¾–1¼ in) | 19–25 mm (¾–1 in) |
| Tread thickness | 25 mm (1 in) typical | 38 mm (1½ in) for open risers |
Source: International Residential Code (IRC) R311.7. Local amendments may apply — always confirm with your architect or building inspector.
Commercial Stairs (OSHA / IBC Standard)
| Dimension | Requirement |
|---|---|
| Tread depth | Min 241 mm (9½ in) at leading edge |
| Tread width at leading edge | Min 178 mm (7 in) |
| Riser height | Max 178 mm (7 in) |
| Stair width | Min 1,118 mm (44 in) for occupant loads over 50 |
Source: OSHA 1910.25; IBC Section 1011. Commercial and industrial projects require a licensed engineer to confirm compliance.
The Ergonomic Formula
A widely used rule for comfortable stair proportions:
2 × riser height + tread depth ≈ 600–640 mm
This formula, sometimes called Blondel’s rule, reflects the natural stride length of a walking adult. A staircase that hits this range feels natural to climb without conscious effort.
Example that works:
- Riser = 170 mm
- Tread depth = 260 mm
- 2 × 170 + 260 = 600 mm ✓
Example that feels steep:
- Riser = 190 mm
- Tread depth = 240 mm
- 2 × 190 + 240 = 620 mm (within range but at the steeper end)
When designing a new staircase, choose a riser height first — one that divides your total floor-to-floor rise into a whole number of steps — then set the tread depth so the formula lands between 600 and 640 mm.
DuraMagicFloor Standard Production Ranges
The table below shows the dimensions we cut to as standard. Sizes outside these ranges are available on request with a custom quote.
| Dimension | Standard Range | Unit |
|---|---|---|
| Longueur | 900–1,300 | mm |
| Depth | 280–300 | mm |
| Épaisseur | 15–25 | mm |
In inches (approximate):
| Dimension | Standard Range | Unit |
|---|---|---|
| Longueur | 35½–51¼ | in |
| Depth | 11–11¾ | in |
| Épaisseur | ⅝–1 | in |
Our standard depth range of 280–300 mm sits comfortably above the IRC minimum of 254 mm, placing it in the comfortable-use zone for residential stairs. Our thickness range of 15–25 mm covers both retrofit applications (thinner boards where subtread height is already fixed) and new construction (thicker boards where the full tread height is part of the design).
Every tread is cut to your exact specification. There is no minimum order quantity.
Stair Shapes: Which One Does Your Staircase Need?
Straight Tread
The standard rectangular board used on a straight-run staircase. Length, depth, and thickness are all that need to be specified.
Curved Tread
Used on bowed or sweeping staircases where the front edge follows a radius. Because the curve must match the specific geometry of that staircase, curved treads are made to a radius specification from a stair plan rather than off a standard size chart.
Winder Tread
Found where a staircase turns a corner without a landing. Winder treads are wedge-shaped — narrower on one side, wider on the other — so each one is effectively a unique shape within the same staircase. These are made to a stair plan.
How to Measure Your Staircase Before Ordering
For replacement treads, measure each step individually rather than assuming they are all identical — particularly on older homes where settling has caused variation.
- Depth — from the front edge of the tread to where it meets the riser behind it, not including the nosing overhang.
- Épaisseur — measure the tread you are replacing directly, or measure the subtread height in new construction.
- Longueur — wall to wall on an enclosed staircase, or edge to edge on an open-sided staircase.
- Note the shape — identify where the staircase is straight, where it sweeps, and where it winds around a corner, since each section needs a different tread shape.
If any steps vary in size — common on staircases older than 30 years — measure every step and flag the variation when you send your order.
Custom Sizes, No Minimum Order
The ranges above cover most residential and light commercial projects. DuraMagicFloor cuts every stair tread — straight, curved, or winder — to the exact length, depth, and thickness you specify. No minimum order quantity applies whether you need one staircase’s worth of treads or a full development project.
From the Factory
Our stair treads are produced at our facilities in Zhejiang, China and Thailand. Every batch is cut to customer specification on CNC equipment, which means the depth, thickness, and length you specify is what arrives — not a stock size trimmed to approximate fit. For projects where treads need to match an existing hardwood floor, we can cut from the same production batch as the flooring order to minimize color and grain variation between the floor and the stairs.
FAQ
What is the minimum tread depth required by building code?
For residential stairs in the United States, the International Residential Code (IRC) sets the minimum tread depth at 254 mm (10 inches), measured horizontally from the front of the nosing to the riser behind it. For commercial stairs, OSHA requires a minimum of 241 mm (9½ inches) at the leading edge. Local codes may set higher minimums — always confirm with your local building department before ordering.
What thickness should a hardwood stair tread be?
For a standard enclosed residential staircase, 25 mm (1 inch) is the most common tread thickness. Open-riser staircases or wide spans often use 38 mm (1½ inches) for additional stiffness. If you are replacing existing treads, match the thickness of the original board so the riser height stays consistent across the staircase.
Can winder treads be made to match the straight treads on the same staircase?
Yes. A winder tread is cut from the same species, finish, and grade as the rest of the staircase — only the shape changes to follow the turn. Send your stair plan and we will cut the winder pieces to match the straight treads exactly.
What happens if my stair tread depth is too shallow?
A tread that falls below code minimum does not give the foot enough surface to land securely, increasing the risk of missteps — particularly when descending. This is why most building codes set a hard minimum for tread depth rather than leaving it to designer discretion. If you are retrofitting an existing staircase that is already undersized, consult a licensed contractor before ordering replacement treads.
Do you supply treads in both metric and imperial sizes?
Yes. We quote and cut to metric dimensions as standard, but can work from imperial measurements. The conversion table above covers our standard production range. When ordering, specify which unit system you are using and we will confirm the dimensions before cutting.
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