What Does “6mm” Mean in Cable Specifications?
When we google ‘6mm’ wire and cable, do we mean 6mm² cable or 6mm diameter cable? This question comes up in some buyers’ minds from time to time.
In this article, as a cable manufacturer and supplier, I will answer this question. Also, you will learn the following:
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What is the outer diameter of a cable, the outer diameter of the conductor, the cross-sectional area
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How to calculate cable cross-sectional area
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Practical examples and calculation methods
1. Understanding Cable Dimensions: OD, Conductor Diameter & Cross-sectional Area
Cable Overall Diameter (OD)
The outer diameter of the cable refers to the overall diameter (OD) of the cable, including the cable insulation (generally plastic or rubber).
For example, the outer diameter of the cable in the figure is 15.33mm.
Because of the limitations of the production process, the outer diameter of the cable is usually allowed to have little difference, especially rubber cables, its standard outer diameter is usually a range rather than a specific value.
For example, the outside diameter of a 50mm2 rubber cable is 18.6-23.3 mm.
Cross-sectional area of the cable
The cross-sectional area of a cable refers to the square meter of the cable. Since wires are generally round, the cable cross-sectional area is the area of its round cross-sectional area, and generally we will use square millimetre (mm²,mm^2, sq mm) as its unit.
#The cross-sectional area mentioned here generally does not include the insulation of the cable, just the copper or aluminium conductor inside.
Commonly the square of the wire is in accordance with the international IEC EN DIN standard to specify (the United States has its own AWG wire gauge does not use mm ²), in daily life we generally speaking how many squares to divide the load carrying capacity of the wire.
So for a cable it is crucial to its cross-sectional area, we according to different cable uses, different loads, to choose different cross-sectional area of the cable. The biggest factor affecting the price is also its cross-sectional area.
Conductor outer diameter
The outer diameter of the conductor is the outer diameter of the circle formed by the copper and aluminium conductors inside the cable. We can use this value to measure the area of the cable.
2. How to Calculate the Cross-sectional Area of a Cable
There are two main ways to calculate mm² area from diameter:
Method A: Simple Circular Area Formula
Example:
If conductor diameter = 0.8mm
→ Area = 3.14 × (0.8 × 0.8 ÷ 4) ≈ 0.5mm²
Method B: Multi-strand Conductor Calculation
We will find that there are inevitable errors in this calculation, and some cables may have an irregular shape instead of a round one. Here I offer another professional method of calculation.
Example (based on IEC 60228):
A 50mm² conductor may consist of 400 strands of 0.40mm diameter copper wires:
→ 0.7854 × 0.4² × 400 = 50.26mm²
This is more accurate for flexible/multi-strand cables.
3. So, Is “6mm Cable” the Same as 6mm²?
The answer is: Yes.
So why do online factories use 6mm to describe it?
Because 6mm² is too hard to type out.
Many people like to type 6mm directly, which will be much easier.
During your communication with the factories, the 6mm in their text messages is 6mm². This is a default premise.
If you’re worried about getting it wrong you can ask the producer to mark it clearly on the contract. At least that’s what we do ourselves.
