Stainless Steel Tube Sizes – Complete Table of Diameters, Wall Thicknesses and Weight

Choosing the correct stainless steel tube size is essential for cost, strength and installation quality. Tube size is normally defined by outside diameter and wall thickness. For example, Ø 42.4 × 2.0 mm means a 42.4 mm outside diameter and a 2.0 mm wall thickness.

Tube size notation

A typical stainless steel tube size is written as Ø 42.4 × 2.0 mm. Ø 42.4 is the outside diameter, while 2.0 mm is the wall thickness. The inside diameter is calculated by subtracting twice the wall thickness from the outside diameter: 42.4 - 2 × 2.0 = 38.4 mm.

DN, NPS and real outside diameter

If a drawing specifies DN 50, the real outside diameter is 60.3 mm, not 50 mm. In the NPS system, 2″ corresponds to the same outside diameter. Decorative and structural tubes are usually specified directly by outside diameter in millimetres rather than by DN or NPS.

Reference table: DN nominal sizes and the matching outside diameters.

Common round tube sizes and weights (table)

Round stainless steel tubes are commonly supplied in diameters from 6 mm to more than 200 mm. Frequently used sizes include Ø 12, Ø 16, Ø 20, Ø 25, Ø 33.7, Ø 38, Ø 42.4, Ø 48.3, Ø 60.3, Ø 76.1, Ø 88.9 and Ø 114.3 mm. Wall thicknesses typically range from 1.0 mm to 6.0 mm depending on the use.

Theoretical weights calculated with the formula below. Reference values for standard dimensions, not a stock list.

Handrails and architectural use

For handrails, Ø 42.4 × 2.0 mm is one of the most common choices. It offers a comfortable grip and enough strength for typical bracket spacing. Ø 33.7 mm is often used for lighter indoor rails, while Ø 48.3 mm is preferred for industrial or heavier-duty installations.

Structural and pressure use

For load-bearing structures, square and rectangular tubes are often preferred because they are easy to connect and align. Common sizes include 40 × 40, 50 × 50, 60 × 60, 80 × 80 and 100 × 100 mm. Pressure applications require calculation and a suitable standard such as EN 10217-7 for welded pressure tubes or EN 10216-5 for seamless pressure tubes.

Square and rectangular tubes

Square stainless steel tubes are common in frames, furniture, railings and support structures. Typical sizes include 20 × 20, 25 × 25, 30 × 30, 40 × 40, 50 × 50, 60 × 60, 80 × 80 and 100 × 100 mm. Rectangular tubes such as 40 × 20, 60 × 40, 80 × 40 and 100 × 50 mm are used when load is mainly applied in one direction.

Wall thickness selection

For decorative tubes that do not carry load, 1.0-1.5 mm is often sufficient. For indoor handrails, 1.5-2.0 mm is typical. Outdoor handrails should normally use at least 2.0 mm, and heavier structures should use 3.0 mm or more. Pressure tubes must be selected according to calculation and the relevant standard, usually EN 10217-7 for welded stainless pressure tubes.

Weight

Tube weight depends on diameter, wall thickness and material density. AISI 304 has a density of approximately 7,900 kg/m³, while AISI 316 is approximately 8,000 kg/m³. The difference in weight between the two grades is small in normal use.

For a round tube, weight can be estimated with: weight = π × (OD - WT) × WT × density / 1,000,000. OD and WT are in millimetres, and density is approximately 7,900 kg/m³ for AISI 304 and 8,000 kg/m³ for AISI 316. Example: Ø 42.4 × 2.0 mm in AISI 304 = π × 40.4 × 2.0 × 7,900 / 1,000,000 = 2.01 kg/m.

Standards

Important standards include EN 10217-7 for welded stainless pressure tubes, EN 10216-5 for seamless stainless pressure tubes, EN 10296-2 for welded structural tubes and EN 10297-2 for seamless structural tubes. EN 10204 3.1 material certificates are commonly required for traceability.

When requesting a quote, provide the outside diameter, wall thickness, material grade, length, quantity, surface finish and certificate requirement. Kominox supplies stainless steel tubes in standard and project-specific sizes.