24 gauge wire measures 0.511 mm across. Its cross-section is 0.205 mm², or 404 circular mils.
The nearest metric size is 0.5 mm² — more than double the conductor. That is not a conversion, and it tells you something useful about how cable at this size is actually chosen.
The metric series does not reach this far
Metric conductor sizes stop at 0.5 mm². There is nothing below it in the standard.
24 AWG is 0.205 mm², which sits well underneath the floor:
| Gauge | Cross-section | Nearest metric | Increase |
|---|---|---|---|
| 20 AWG | 0.519 mm² | 0.5 mm² | −4% |
| 22 AWG | 0.324 mm² | 0.5 mm² | +54% |
| 24 AWG | 0.205 mm² | 0.5 mm² | +144% |
| 26 AWG | 0.128 mm² | 0.5 mm² | +291% |
At 20 AWG the two systems still line up. Two gauges further down, the metric equivalent has two and a half times the copper.
A 24 AWG conductor runs about 84.22 Ω/km against the 36.0 Ω/km limit for 0.5 mm². It misses by 134%. These are not two descriptions of the same conductor — they are different cables.
So how is 24 AWG actually specified?
Not by cross-section. This is the point where conductor selection stops being about area and starts being about signal behaviour.
24 AWG is the standard conductor in structured cabling, telephone pairs, and a large share of instrumentation and data cable. In those applications the cable is specified by:
Characteristic impedance. A twisted pair for data has a target impedance — 100 Ω for structured cabling is the common case. That is set by the conductor diameter, the insulation thickness and the twist rate together. Change the gauge and you change the impedance, which is why substituting a “bigger” conductor breaks the cable rather than improving it.
Capacitance per unit length. Rise time on a differential pair degrades with cable capacitance, so data cable is specified in pF/m. A thicker conductor at the same insulation thickness generally raises capacitance.
Loop resistance. On a long run, 84.22 Ω/km means 168 Ω in a 1,000 m out-and-back loop. That matters for powered devices and for 4-20 mA loops, where the resistance is part of the circuit budget.
None of those are area calculations, and none of them are improved by rounding up to 0.5 mm².
What that means in practice
If you find 24 AWG on a drawing and want the metric equivalent, the honest answer is that there is not one. The nearest metric size is 0.5 mm², and it is a different cable with different electrical behaviour.
For a data or instrumentation pair, source cable to the applicable cabling standard rather than converting the gauge. For a low-current power or control conductor where only the resistance matters, 0.5 mm² will do the job with a large margin.
Do not substitute a 0.5 mm² conductor into a controlled-impedance pair and expect it to work.
Conductor diameter
0.511 mm is solid wire, and solid 24 AWG is common in structured cabling — many cable types specify solid conductor for permanent links and stranded for patch cords.
At the nearest metric size, 0.5 mm², the maximums are:
| Construction | Max diameter | Max strand dia. |
|---|---|---|
| Class 1, solid | 0.9 mm | — |
| Class 2, stranded | 1.1 mm | — |
| Class 5, flexible | 1.1 mm | 0.21 mm |
| Class 6, very flexible | 1.1 mm | 0.16 mm |
Those figures describe a conductor with more than twice the copper of 24 AWG, so treat them as context rather than as specifications for this gauge. See conductor classes 1, 2, 5 and 6.
Where 24 AWG is used
Structured cabling and network patch cable, telephone pairs, instrumentation and signal wiring, ribbon cable, internal equipment wiring, and low-current control connections.
FAQ
How many mm is 24 gauge wire?
0.511 mm in diameter for solid wire, which is 20.1 mils. Stranded 24 AWG is wider.
What is 24 AWG in mm²?
0.205 mm². The smallest metric size is 0.5 mm², which is 144% larger — so there is no close metric equivalent.
Is 24 AWG the same as 0.5 mm²?
No, and not approximately. 0.5 mm² has nearly two and a half times the copper, and a 24 AWG conductor misses its resistance limit by 134%.
Can I use 0.5 mm² instead of 24 AWG?
For a low-current control conductor where only resistance matters, yes, with a large margin. For a controlled-impedance data pair, no — changing the conductor changes the impedance and the capacitance, and the cable will not perform to the cabling standard.
Why is there no metric size below 0.5 mm²?
The metric conductor standard starts at 0.5 mm². Finer conductors are covered by the standards for the cable type — telecommunications and data cabling — rather than by the general conductor standard.
Is 24 gauge or 22 gauge thicker?
22 gauge. Lower AWG numbers are thicker. 22 AWG is 0.643 mm against 0.511 mm, and it has 58% more copper.
Reference
| Property | 24 AWG |
|---|---|
| Diameter, solid | 0.511 mm |
| Diameter, solid | 20.1 mils / 0.0201 in |
| Cross-sectional area | 0.205 mm² |
| Area | 404 cmil |
| Resistance, solid copper at 20 °C | 84.22 Ω/km |
| Nearest metric size | 0.5 mm² (+144%) |
| Metric size below | none — 0.5 mm² is the floor |
Convert any other gauge with the AWG to mm² converter, or read why AWG and metric sizes never line up.