Wire Gauge (AWG) Chart
The American Wire Gauge table for bench and LED work: diameter, cross-section, resistance per metre and how much current a conductor can carry. Two different limits hide in this chart (ampacity and voltage drop), and hobby projects usually hit the second one first.
The tableConversion rulesWorked exampleFAQ
Three patterns worth memorising.
Every three gauges roughly doubles the cross-section (18 to 15). Every six doubles the diameter (18 to 12). Every ten multiplies resistance by about ten (20 to 10). That is enough to sanity-check any table you meet.
The table
| AWG | Diameter (mm) | Area (mm²) | Resistance (Ω/km) | Chassis (A) | Power transmission (A) |
|---|---|---|---|---|---|
| 10 | 2.588 | 5.26 | 3.277 | 55 | 15 |
| 12 | 2.053 | 3.31 | 5.211 | 30 | 9.3 |
| 14 | 1.628 | 2.08 | 8.286 | 25 | 5.9 |
| 16 | 1.291 | 1.31 | 13.17 | 22 | 3.7 |
| 18 | 1.024 | 0.823 | 20.95 | 16 | 2.3 |
| 20 | 0.812 | 0.518 | 33.31 | 11 | 1.5 |
| 22 | 0.644 | 0.326 | 52.96 | 7 | 0.92 |
| 24 | 0.511 | 0.205 | 84.22 | 3.5 | 0.577 |
| 26 | 0.405 | 0.129 | 133.9 | 2.2 | 0.361 |
| 28 | 0.321 | 0.081 | 212.9 | 1.4 | 0.226 |
Chassis = single conductors in free air, short bench runs. Power transmission = bundled or enclosed runs where heat cannot escape. When in doubt use the lower number and then check the voltage drop anyway: insulation can survive a current that the electronics at the far end cannot.
Converting to mm²
European wire is sold by cross-section, so the mapping you actually need: 0.5 mm² ≈ 20 AWG, 0.75 ≈ 18, 1.0 ≈ 17, 1.5 ≈ 15, 2.5 ≈ 13, 4.0 ≈ 11. A 2.5 mm² hookup wire sits between AWG 12 and 14, which is why "2.5 mm²" and "14 AWG" are close but not the same job.
Worked example: when ampacity lies to you
A 5 m strip run at 12V pulling 5 A over 18 AWG: the ampacity column says 16 A, so heating is not the problem. The far end still browns out: 10 m round trip times 23 mΩ/m is 0.23 Ω, so 5 A drops 1.15 V, 9.6% of the supply. That is the voltage drop limit, not the current limit. Check your own run with the voltage drop calculator.
FAQ
Why does a smaller gauge number mean thicker wire?
AWG counts the drawing steps the wire went through: each step thins it, so a higher number means more steps and a thinner conductor. That is why 10 AWG is beefier than 24 AWG.
Which ampacity column should I use?
Chassis wiring for short runs in open air; power transmission for anything bundled, sleeved or long, where heat cannot escape. Automotive, LED and battery projects are almost always closer to the second column than the first.
What about the wire already in cheap jumper leads?
Most patch leads and dupont wires are 26 to 28 AWG with thin strands: fine for signals, painful for current. If a sensor works on a breadboard and browns out on a long lead, the lead is the first suspect.
Does insulation matter?
Yes, twice. It sets a temperature limit (silicone survives far more than PVC) and it traps heat when bundled. Silicon insulation is not a licence to exceed the copper rating.
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