One buyer sends us a photo of their wire and a spec that says 14 AWG. Another, a European buyer, sends a spec that says 2.5 mm2. Both are describing roughly the same wire, and both can be right. The confusion is not the wire. It is that two measurement systems ended up living on the same small metal part, and nobody ever sits buyers down to explain it. We make terminals that ship to both markets, so here is the explanation we give our own sales team, in plain English.
Why does the same terminal have two size markings?
Because the barrel has to fit a band of wire, and different regions name that band differently. On our barrels you will typically see a marking like 16-14 AWG, and in some cases the metric equivalent as well. The range is deliberate: a crimp barrel is sized for a band of conductor diameters, not a single wire. One 16-14 barrel will grip 16 AWG and 14 AWG solid or stranded wire. The dual marking is just the factory telling you the same range in both languages. Read it as one number, not two options.
This is why the same barrel you buy in the US might arrive with a slightly different printed marking in Europe: the factory localizes the label for the market. The metal inside has not changed. When in doubt, trust the barrel diameter, not the ink.
AWG vs mm2: what are the actual conversions?
Here is the table we keep taped inside a cabinet. AWG is a diameter-based system where a lower number means a thicker wire. mm2 is the cross-sectional area of the copper. The right-hand column is the standard wire size your supplier will actually stock, because metric markets buy in fixed steps: 0.5, 1, 1.5, 2.5, 4, 6, 10, 16 and 25.
|
AWG |
Copper area (mm2) |
Nearest standard wire size |
|
22 AWG |
0.33 mm2 |
0.5 mm2 |
|
20 AWG |
0.52 mm2 |
0.75 mm2 |
|
18 AWG |
0.82 mm2 |
1.0 mm2 |
|
16 AWG |
1.31 mm2 |
1.5 mm2 |
|
14 AWG |
2.08 mm2 |
2.5 mm2 |
|
12 AWG |
3.31 mm2 |
4 mm2 |
|
10 AWG |
5.26 mm2 |
6 mm2 |
|
8 AWG |
8.37 mm2 |
10 mm2 |
|
6 AWG |
13.3 mm2 |
16 mm2 |
|
4 AWG |
21.2 mm2 |
25 mm2 |
Do not convert blindly and order the raw result. The middle column is the copper area of the AWG wire; the right column is the standard stock size it maps to in metric markets. When a buyer in Europe says 2.5 mm2, the AWG side of the barrel that fits it is 14. When a buyer in the US says 14 AWG, the metric label for the same barrel is the 1.5 to 2.5 range. Same part, two labels.
What does 16-14 AWG on the barrel actually mean for my wire?
It means the barrel is sized to grip 16 or 14 AWG conductor, stranded or solid, with the insulation stripped to the correct length. If your wire is 18 AWG, that barrel is one step too big, and the crimp will be loose. If your wire is 12 AWG, the barrel is too small and will not close cleanly. The range covers the two nominal sizes in it, not everything in between. If your wire sits awkwardly between standards, measure its outer diameter after stripping and send us the number. Fit is a physical fact, and a caliper settles arguments that tables start.
One more thing the table does not say: it applies to solid and stranded wire alike. A barrel sized for a given gauge grips the conductor bundle, not the strand count, so the same 16-14 barrel works for 16 AWG solid or 16 AWG fine-strand. What does change with stranded wire is the stripping length, and that is a workmanship detail, not a sizing one.
What actually goes wrong when the size is wrong?
A terminal one size too big gives you a loose crimp. It passes a casual pull, it looks fine in the box, and then it works itself free under vibration, or it runs hot under load because the contact resistance is too high. That is the quiet failure, and it is the one that ends up back at the supplier’s door three years later. A terminal one size too small is the loud failure: strands get cut, the barrel will not fully close, the insulation gets crushed, and the connection is intermittent from the first power-on. Both directions fail in the field, not in the carton. Sizing is the one part of terminal selection that has no room for close enough.
A practical cheat sheet for ordering
- 5 to 1 mm2 (22-18 AWG): instrumentation, signal wiring, small devices
- 5 to 2.5 mm2 (16-14 AWG): the workhorse range for control panels and harnesses; if you are unsure, most of your volume will sit here
- 4 to 6 mm2 (12-10 AWG): equipment power, motors, distribution inside machines
- 10 to 16 mm2 (8-6 AWG): heavy feeds, where flat lugs start to replace round Ring Terminals
If you are new to ordering terminals by gauge, here is the fastest way to stop guessing. Photograph your wire with the jacket on, then strip a few centimeters and measure the bare conductor diameter with a caliper. Send the photo, the measured diameter, and the application – control panel, harness, or power feed – to the supplier. We map that diameter to the right barrel range in one reply, because we carry the dual AWG and mm2 marking on the same part. It takes you two minutes, and it removes the single biggest source of wrong-size orders we see: the buyer who converted a spec by hand and rounded the wrong way.
When you send us an inquiry, the three things that make the reply instant are the wire size in either system, the insulation type you need, and the quantity. Anything else, we figure out together.
We are Yueqing Gaopeng Electric, a terminal manufacturer in Yueqing since 2016, with in-house molds, ISO 9001 process control, and CE and RoHS compliance. If a spec sheet has two numbers on it and you are not sure which to order, send us both and a photo of your wire. We will tell you the exact barrel to buy before you spend a cent.
