Wire gauge charts cause confusion for one reason: a metric wire size like "1.5 mm" usually means the conductor's cross-sectional area (1.5 mm²), not its diameter. AWG is a separate numbering system. This guide gives you the conversion both ways, shows the maths behind it, and helps you pick the right size of connector.
Quick answer: common metric sizes in AWG
Metric cable is sold by conductor cross-section in square millimetres (mm²). Use this table when your cable is marked 0.5, 0.75, 1.0, 1.5, 2.5, 4 or 6 mm².
| Metric cable (mm²) | Exact AWG equivalent | Nearest standard AWG | Solderin connector (by mm² range) |
|---|---|---|---|
| 0.25 mm² | 23.1 | 23 AWG | White (26-24 AWG) |
| 0.34 mm² | 21.8 | 22 AWG | White (26-24 AWG) |
| 0.5 mm² | 20.1 | 20 AWG | Red (22-18 AWG) |
| 0.75 mm² | 18.4 | 18 AWG | Red (22-18 AWG) |
| 1 mm² | 17.2 | 17 AWG | Red (22-18 AWG) |
| 1.5 mm² | 15.4 | 15 AWG | Blue (16-14 AWG) |
| 2.5 mm² | 13.2 | 13 AWG | Blue (16-14 AWG) |
| 4 mm² | 11.2 | 11 AWG | Yellow (12-10 AWG) |
| 6 mm² | 9.4 | 9 AWG | Yellow (12-10 AWG) |
| 10 mm² | 7.2 | 7 AWG | Outside our connector range |
| 16 mm² | 5.2 | 5 AWG | Outside our connector range |
So 1.5 mm² is about 15 AWG, 2.5 mm² is about 13 AWG, 1 mm² is about 17 AWG and 0.5 mm² is about 20 AWG. Metric and AWG sizes do not line up exactly, so the "exact" column shows the decimal equivalent. If you must substitute, choose the thicker wire (the lower AWG number), never the thinner one.
AWG to mm: diameter and cross-section
This table gives the bare conductor size for each even AWG number. It excludes the insulation, so the outside of the cable will measure larger.
| AWG | Conductor diameter (mm) | Cross-section (mm²) |
|---|---|---|
| 26 AWG | 0.40 | 0.13 |
| 24 AWG | 0.51 | 0.20 |
| 22 AWG | 0.64 | 0.33 |
| 20 AWG | 0.81 | 0.52 |
| 18 AWG | 1.02 | 0.82 |
| 16 AWG | 1.29 | 1.31 |
| 14 AWG | 1.63 | 2.08 |
| 12 AWG | 2.05 | 3.31 |
| 10 AWG | 2.59 | 5.26 |
| 8 AWG | 3.26 | 8.37 |
| 6 AWG | 4.12 | 13.30 |
What if "mm" means diameter?
Sometimes a wire is described by its conductor diameter, for example "1 mm wire" measured with callipers. Diameter and cross-section give very different answers, so check which one you have before you convert.
| Conductor diameter | Approx. AWG |
|---|---|
| 0.5 mm | 24.2 |
| 1 mm | 18.2 |
| 1.5 mm | 14.7 |
| 2 mm | 12.2 |
| 2.5 mm | 10.3 |
| 5 mm | 4.3 |
For example, a conductor 1 mm in diameter is about 18 AWG, but a 1 mm² cable is about 17 AWG. A 2.5 mm diameter conductor is about 10 AWG, while 2.5 mm² cable is about 13 AWG. Measure the bare metal, not the insulation. For stranded wire, measuring diameter is unreliable; use the size printed on the cable.
Is gauge the same as AWG?
Often, but not always. In North America, "wire gauge" or "gauge" on electrical wire almost always means AWG (American Wire Gauge). Other gauge systems exist:
- SWG (British Standard Wire Gauge): an older UK system. Its numbers do not match AWG. For example, 18 SWG is about 1.22 mm diameter, while 18 AWG is about 1.02 mm.
- Sheet metal gauge: a different scale again, used for sheet thickness, not wire.
- Metric (mm²): used in Australia, the UK, Europe and most of the world for cable.
With every gauge system, a higher number means a thinner wire.
How the conversion works
AWG is a logarithmic scale defined from two fixed points: 36 AWG is 0.127 mm and 0000 (4/0) AWG is 11.684 mm. Every step of 6 gauges roughly halves the diameter, and every step of 3 gauges roughly halves the cross-section.
- Diameter (mm) = 0.127 × 92(36 − AWG) / 39
- Cross-section (mm²) = π ÷ 4 × diameter²
- AWG from diameter = 36 − 39 × log92(diameter ÷ 0.127)
Choosing a wire size
The right gauge depends on the current, the cable length (voltage drop), the insulation type, how the cable is bundled or enclosed, and the wiring rules that apply where you are. This guide converts sizes; it does not tell you how much current a cable can carry. Check the current rating from your cable manufacturer and follow the applicable standard. When in doubt, use a licensed electrician.
Matching a connector to your wire
Solderin heat shrink solder connectors (also called solder seal or solder sleeve connectors) are colour-coded by wire size. Pick the colour that covers your wire gauge:
| Connector | Wire gauge | Metric cable |
|---|---|---|
| White | 26-24 AWG | 0.25-0.34 mm² |
| Red | 22-18 AWG | 0.5-1.0 mm² |
| Blue | 16-14 AWG | 1.5-2.5 mm² |
| Yellow | 12-10 AWG | 4.0-6.0 mm² |
Our connector sizes are listed in both AWG and mm². The two ranges are rounded and do not line up exactly at the edges (for example, 0.34 mm² is closer to 22 AWG than 24 AWG). For metric cable, go by the mm² range. For AWG wire, go by the AWG range. If your wire sits on a boundary, check the fit before you heat the connector.
Joining two different sizes? Choose the connector that fits the larger wire. If your cable sits outside these ranges, a different connector is the right call. For a mix of sizes, the assorted connector kits include all four colours in a storage box.
