Metric to AWG Wire Size Conversion Chart

Metric conductors are sized by cross-sectional area in square millimetres and AWG conductors by a gauge number, and the two series were never designed to line up. No metric size has an exact AWG equivalent. The table below gives the closest gauge for each standard metric size and, separately, the nearest gauge that is not smaller — which is the one to use when the metric size was a requirement rather than a description.

Two columns, because closest is not always right

A conversion chart owes you the arithmetically closest answer, and that is the first AWG column. But closest can be smaller. three of the sizes below resolve that way — 35 mm², 70 mm² and 95 mm² each land on a gauge with less conductor in it than the metric size it replaces — and substituting one of those is a downgrade however close the numbers look. The last column gives the nearest gauge that is not smaller, so the choice is explicit rather than accidental.

This is a dimensional chart and nothing more. What a conductor may actually carry depends on insulation, grouping, ambient temperature, length and the installation code in force — none of which a size conversion knows anything about. Use it to identify wire and to order it, not to decide what it can be asked to do.

Metric conductor sizes to AWG

Method and precision

Metric sizes are the nominal cross-sections defined by IEC 60228. AWG values are the published table (ASTM B258), listed as published rather than recomputed; every row is cross-checked against the defining expression, diameter = 0.005 in multiplied by 92 to the power (36 minus n) over 39, and against its own geometry, area = pi/4 times diameter squared. The list stops at 95 mm² because the AWG series ends at 4/0, and pairing anything larger against it would be extrapolation rather than conversion. Areas are conductor cross-sections, not overall cable diameters.

The full AWG table

Gauge numbers run backwards: the bigger the number, the thinner the wire, and the series continues past zero as 1/0, 2/0, 3/0 and 4/0 rather than into negative numbers. Two rules of thumb fall out of the geometry and are worth carrying: six gauges up doubles the diameter and so roughly quadruples the area, and three gauges up roughly doubles the area on its own. 16 AWG is 1.31 mm², 13 AWG is 2.62 mm², and 10 AWG is 5.26 mm².

Where the two systems land differently

The gaps are widest at the small end. 0.75 mm² sits between 19 and 18 AWG with nothing close on either side, and 1 mm² is similar. In the middle the fit improves — 4 mm² and 11 AWG are within a few per cent — and at the large end it degrades again as the AWG series runs out entirely above 4/0. There is no rule of thumb that covers the whole range, which is the reason for the table.

Cutters, strippers and crimps are in pliers, and anything for work on or near live conductors is in insulated tools. Calipers for measuring a conductor directly are in measuring equipment.