2/0 AWG in mm: The Feeder Size That Converts Cleanly

2/0 AWG measures 9.26 mm across. Its cross-section is 67.4 mm², or 133,100 circular mils.

Of the eighteen gauges on this site, this is one of two that converts to metric without a compromise.

It meets the 70 mm² requirement

Metric cable is verified by DC resistance per kilometre at 20 °C, not by measuring copper. Almost every AWG conductor fails the limit of the metric size it rounds up to, because the round-up leaves it smaller than nominal. 2/0 does not:

67.4 against 70 mm² is a 4% gap, small enough that the conductor stays inside the limit.

The only other gauge that manages this is 2 AWG against 35 mm², also at 4%. Two kcmil sizes behave the same way — 350 kcmil against 185 mm² and 750 kcmil against 400 mm². Four points in the whole system, and that is the complete list.

Everywhere else you are rounding up and accepting extra copper. Here the substitution holds on the number that gets tested. See why AWG doesn't match metric sizes.

It also clears the size below

2/0 at 0.256 Ω/km comfortably meets the 50 mm² limit of 0.387 Ω/km as well.

So both metric sizes either side are technically available:

The resistance test does not rule out 50 mm², but the ampacity difference does the ruling instead — 144 A against 175 A is a 21% drop in what the conductor carries. On a feeder that is not a rounding decision.

70 mm² is the answer. It is 4% larger, it costs almost nothing extra, and it is the closest clean pairing available at feeder scale.

Ampacity

2/0 copper carries 145 A at 60 °C, 175 A at 75 °C, and 195 A at 90 °C, for three current-carrying conductors at 30 °C ambient. 70 mm² with three loaded conductors clipped direct at 30 °C is 184 A for PVC and 229 A for XLPE.

Derating applies to all of it. 70 mm² XLPE in a 40 °C switchroom with two circuits together:

229 A  ×  0.91 (40 °C)  ×  0.80 (2 circuits)  =  167 A

The terminal rating at each end usually caps which ampacity column you may use, regardless of the cable insulation.

Conductor diameter

9.26 mm is solid wire, and nothing at this size is solid. At 70 mm²:

13.1 mm against 9.26 mm is a 41% spread. Compression lugs at this scale are ordered before the cable arrives, so take the diameter from the manufacturer's data for the construction you are actually buying. See conductor classes 1, 2, 5 and 6.

Where 2/0 is used

Service entrance conductors, sub-main feeders, larger motor circuits, welding cable, and battery and inverter connections in solar and standby systems. It is also common in parallel runs, where two 2/0 conductors are used in place of one larger cable to keep the pull and the terminations manageable.

FAQ

What is 2/0 AWG in mm?

9.26 mm in diameter as solid wire, which is 364.8 mils. Stranded 2/0 measures up to 11.0 mm and flexible up to 13.1 mm at the equivalent metric size.

What is 2/0 AWG in mm²?

67.4 mm². The metric cable size to order is 70 mm², only 4% larger.

Is 2/0 the same as 70 mm²?

Closer than almost any other pairing. 70 mm² has 4% more copper, and a 2/0 conductor does meet the 70 mm² resistance limit — which is true of only one other gauge. For most practical purposes they are interchangeable. Check the product standard for the specific cable type before committing.

Can I use 50 mm² instead of 2/0?

50 mm² meets its own resistance limit, but it has 26% less copper and carries 144 A against the 175 A of 2/0 at 75 °C. That is a significant reduction on a feeder.

What does 00 mean on a cable?

It is another way of writing 2/0. The 0-series is written either 1/0, 2/0, 3/0, 4/0 or 0, 00, 000, 0000.

How many amps is 2/0 copper?

145 A at 60 °C, 175 A at 75 °C, 195 A at 90 °C, before derating for ambient temperature and conductor grouping.

Reference

Convert any other size with the AWG to mm² converter, or see the other clean pairing at 2 AWG.