Most converters will tell you 1.5 mm² is 16 AWG. That is arithmetically correct and practically wrong.
16 AWG is 1.31 mm² — 13% less copper than 1.5 mm². Install it against a 1.5 mm² design and you have quietly reduced what the circuit can carry.
14 AWG is the gauge to order.
Table of Contents
The gap between the two candidates
| Gauge | Cross-section | Against 1.5 mm² | |
|---|---|---|---|
| Closest by area | 16 AWG | 1.31 mm² | 13% less |
| Safe substitute | 14 AWG | 2.08 mm² | 39% more |
39% is a large overshoot, and it is fair to ask whether it is necessary. The answer is in the resistance limit.
16 AWG fails the test
Metric conductors are verified by DC resistance per kilometre at 20 °C. For 1.5 mm² the maximum is 12.1 Ω/km for solid and stranded, 13.3 Ω/km for flexible.
| Gauge | Actual resistance | 1.5 mm² limit | Result |
|---|---|---|---|
| 16 AWG | 13.19 Ω/km | 12.1 | fails by 9% |
| 14 AWG | 8.28 Ω/km | 12.1 | passes |
16 AWG misses by 9%. Not catastrophic, but enough that a conductor resistance measurement against a 1.5 mm² specification will not pass.
There is no gauge between 16 and 14 — the AWG series steps straight from 1.31 mm² to 2.08 mm² with nothing in between. So 14 AWG it is, and the 39% overshoot is the price of the two systems not aligning.
Conductor diameter
A solid conductor of 1.5 mm² works out to 1.382 mm across. The standard specifies maximum diameters by class rather than a nominal value:
| Construction | Max diameter | Min strands | Max strand dia. |
|---|---|---|---|
| Class 1, solid | 1.5 mm | 1 | — |
| Class 2, stranded | 1.7 mm | 7 | — |
| Class 5, flexible | 1.8 mm | — | 0.26 mm |
| Class 6, very flexible | 1.8 mm | — | 0.16 mm |
Solid 16 AWG is 1.29 mm and solid 14 AWG is 1.63 mm, so the whole family sits between roughly 1.3 and 1.8 mm.
Note that class 5 and class 6 share both the diameter maximum and the resistance limit here. The only thing separating them is strand fineness, 0.26 mm against 0.16 mm — and that is what decides whether the cable survives repeated flexing. Full detail in conductor classes 1, 2, 5 and 6.
Where 1.5 mm² is used
Lighting circuits across most of the metric world, plus control wiring, and the smaller side of general power. It is the metric counterpart to 14 AWG in North American practice, even though the two are not the same size.
That functional pairing is worth holding onto. 1.5 mm² does the job 14 AWG does, and 2.5 mm² does the job 12 AWG does, even though the arithmetic pairs them differently. When you are reading a foreign drawing, the functional match tells you what the designer intended; the conversion tells you what to order.
FAQ
What is 1.5 mm² in AWG? 16 AWG by cross-sectional area. But 16 AWG is 1.31 mm², 13% smaller, and it does not meet the 1.5 mm² resistance limit. 14 AWG is the substitute to order.
Can I use 16 AWG for a 1.5 mm² circuit? It has 13% less copper and misses the conductor resistance requirement by about 9%. On a short lighting run it may make no practical difference. On a specification, or on a long run where voltage drop matters, it does.
Is 1.5 mm² the same as 14 AWG? No. 14 AWG is 2.08 mm², about 39% larger. It is the nearest gauge that is not smaller than 1.5 mm², which makes it the safe substitute rather than an equivalent.
What is 1.5 mm² in mm diameter? A solid conductor of 1.5 mm² is 1.382 mm across. Stranded versions measure up to 1.7 mm, flexible up to 1.8 mm.
Why is there no AWG size between 16 and 14? The gauge series steps by a fixed geometric ratio, so the areas fall where they fall — 1.31 then 2.08 mm², with nothing between. See how the AWG system works.
Is 1.5 mm² enough for lighting? It is the standard lighting circuit size in most metric wiring practice, but the actual rating depends on installation method, insulation temperature rating, ambient temperature and grouping. Check the regulations that apply where you are installing.
Reference
| Property | 1.5 mm² |
|---|---|
| Closest AWG by area | 16 AWG (1.31 mm², −13%) |
| Safe substitute | 14 AWG (2.08 mm², +39%) |
| Equivalent solid diameter | 1.382 mm |
| Max resistance, class 1 and 2 | 12.1 Ω/km |
| Max resistance, class 5 and 6 | 13.3 Ω/km |
| Max conductor diameter | 1.5 / 1.7 / 1.8 mm by class |
| Minimum strands, class 2 | 7 |
Work the other direction from 16 AWG or 14 AWG, or use the converter.