4130 Tubing Dimensions Chart
4130 tubing is produced mainly in inch sizes, while many drawings are metric. A dimensions chart helps you translate between the two and see which inch size is closest to the metric dimension you need.
Specifying Dimensions
When ordering globally, it is best practice to specify the exact decimal inch dimension, even if your local drawings are in metric. The manufacturing tooling for ASTM A519 CDS is typically based on inch dimensions. Converting a hard metric requirement (e.g., exactly 25.00mm) to the closest imperial size (1.000" = 25.4mm) may require design adjustments on your end.
Common Imperial to Metric Conversions
Below are the exact metric equivalents (1 inch = 25.4 mm) for common 4130 ODs and wall thicknesses.
| Imperial Dimension (Inches) | Metric Equivalent (mm) | Dimension Type |
|---|---|---|
| 0.035" | 0.89 mm | Wall Thickness |
| 0.065" | 1.65 mm | Wall Thickness |
| 0.083" | 2.11 mm | Wall Thickness |
| 0.120" | 3.05 mm | Wall Thickness |
| 1.000" | 25.40 mm | Outside Diameter |
| 1.500" | 38.10 mm | Outside Diameter |
| 1.750" | 44.45 mm | Outside Diameter |
Working Between Inch and Metric Sizes
Multiply inches by 25.4 to get millimetres. Common conversions are 0.750" = 19.05 mm, 1.000" = 25.4 mm, 1.250" = 31.75 mm, 1.500" = 38.1 mm and 1.750" = 44.45 mm. For walls, 0.049" = 1.24 mm, 0.065" = 1.65 mm, 0.083" = 2.11 mm, 0.095" = 2.41 mm and 0.120" = 3.05 mm.
An inch tube is seldom an exact match for a metric drawing. A design that asks for 40 × 2 mm will not be met by 1.500" × 0.083", which is 38.1 × 2.11 mm. Decide whether the nearest inch size is acceptable or whether a true metric tube to a European standard is required, in which case the grade is normally 25CrMo4; see EN 25CrMo4 tubing. For the full list of inch sizes see the size chart.
Frequently Asked Questions
Can I order 4130 tubing in true metric sizes?
True metric OD sizes (e.g., exactly 40.0mm) are available from mills drawing to EN standards (like 25CrMo4 to EN 10297). Standard ASTM A519 4130 stock is almost universally drawn to inch dimensions. If you require true metric ODs, specify EN 25CrMo4 or request a custom mill run.
How do I convert a tube size from inches to millimetres?
Multiply both the OD and the wall by 25.4. For example 1.500" × 0.095" is 38.1 mm × 2.41 mm.
Which dimensions are toleranced on 4130 tubing?
Cold drawn tube is normally toleranced on two of OD, ID and wall. State which two matter for your part, because all three cannot be held tightly at once.
Is a 38 mm tube the same as 1.500"?
No. 1.500" is 38.1 mm. The difference is small but matters for close fits and bend tooling.
Confirm Dimensional Availability
Provide your dimensions in inches or mm. We will quote the exact matching standard size.
- OD & Wall (in/mm)
- Standard (ASTM or EN)
- Footage
- MTC required
- Delivery