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AWG to mm² Wire Size Calculator

Convert American Wire Gauge to a metric conductor cross-section and back, with the nearest standard size in the other system.

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Which way round the conversion runs.

Going from AWG you get an exact area and the metric size that sits nearest. Going from mm² you get the gauge that is not smaller, and the area you would actually receive if you bought it.

The gauge on the cable jacket or the drawing.

Gauge numbers run backwards — 14 AWG is thinner than 12, and each three steps roughly doubles the area. Above 1 AWG the numbering turns over and sizes are written 1/0 through 4/0, which are progressively thicker.

Conductor cross-section

13.3 mm²

High confidence

6 AWG is 13.30 mm². The geometry is exact — AWG is a defined ratio series — but no metric size lands on it, which is why both the nearest size and the nearest size that is not smaller are given.

Conductor diameter
0.16 in
Nearest standard metric size
0.02 in²
Nearest metric size that is not smaller
0.02 in²
Difference from that size
20.28 %
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • AWG is defined geometrically: 4/0 is 0.4600 in and 36 AWG is 0.0050 in, with 39 equal ratio steps between them, so diameter = 0.005 in × 92^((36 − n)/39)
  • NEC Chapter 9, Table 8 (conductor properties) gives the same areas to three significant figures: 12 AWG = 3.31 mm², 6 AWG = 13.3 mm², 4/0 AWG = 107 mm²
  • IEC 60228 nominal cross-sectional areas for standard metric conductors: 0.5, 0.75, 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400 mm²

Inputs used

Convert
AWG → mm²
AWG size
6 AWG
Conductor cross-section (mm²)
16

Intermediate steps

Conductor diameter
0.16 in
Nearest standard metric size
0.02 in²
Nearest metric size that is not smaller
0.02 in²
Difference from that size
20.28 %
Final result13.3 mm²

Confidence note: 6 AWG is 13.30 mm². The geometry is exact — AWG is a defined ratio series — but no metric size lands on it, which is why both the nearest size and the nearest size that is not smaller are given.

What this calculation does not cover

  • An exact equivalent almost never exists, so every use of this number is a substitution, and substitution is an ampacity decision rather than an arithmetic one. Insulation temperature rating, installation method, ambient temperature, conduit fill and the rating of the terminals all bear on whether a size that matches on area is acceptable in a particular circuit.
  • The two systems' standard sizes interleave rather than align. 6 AWG sits between 13 and 16 mm², 4 AWG between 21 and 25 mm² — so a designer working to one standard and buying to the other is always choosing to round up or down, and rounding down is the direction that removes margin.
  • Nothing here checks voltage drop. Two conductors of the same area have the same resistance per metre whatever they are called, but the run length, load and acceptable drop decide the size at least as often as ampacity does, and on a long run they decide it outright.

Add the equipment this sizes

This result is a specification — 13.3 mm² — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-11 · v1.0.0

Regulatory standards & verification citations3
  1. AWG is defined geometrically: 4/0 is 0.4600 in and 36 AWG is 0.0050 in, with 39 equal ratio steps between them, so diameter = 0.005 in × 92^((36 − n)/39)
  2. NEC Chapter 9, Table 8 (conductor properties) gives the same areas to three significant figures: 12 AWG = 3.31 mm², 6 AWG = 13.3 mm², 4/0 AWG = 107 mm²
  3. IEC 60228 nominal cross-sectional areas for standard metric conductors: 0.5, 0.75, 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400 mm²

Which documents these citations point at

  • National Electrical Code (NFPA 70) — Chapter 9 (United States)Electrical installations — conductor sizing and protection, load calculation, wiring methods, grounding and working clearances.

A code or standard has force only where a jurisdiction has adopted it, usually with local amendments. This site holds no adoption data for any authority, so check what is in force with the authority where you build. Any section cited above without an edition should be checked against the edition in force where you build. What it would take to know.

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Called something else where you work? Gauge — the term in each market, how close the equivalence really is, and the standard that governs it.

The data behind it: Copper conductor sizes and ampacity

How to calculate AWG to mm² wire size in 4 steps

  1. ConvertWhich way round the conversion runs.
  2. AWG sizeThe gauge on the cable jacket or the drawing.
  3. Conductor cross-section (mm²)The metric conductor size, as printed on the cable or given in the specification.
  4. Conductor cross-sectionThe tool computes the conductor cross-section from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

Why is there no metric size that matches my gauge?
Because the two systems were built from different starting points and never reconciled. AWG is a geometric series — 39 equal ratio steps between 36 AWG at 0.005 in and 4/0 at 0.46 in — while the metric sizes are a preferred-number series chosen for round cross-sections. They interleave. 6 AWG is 13.3 mm², which sits between the standard 10 and 16, and no amount of arithmetic will make it land on either.
Should I round up or down when substituting?
Up, unless someone qualified has checked the circuit and decided otherwise. This page picks the size that is not smaller for exactly that reason. Rounding down removes margin from a conductor whose size was set by ampacity or voltage drop, and the shortfall does not announce itself — the circuit works, warm, until the day the load is at its maximum on a hot afternoon.
Why do gauge numbers get smaller as the wire gets thicker?
It is a drawing count rather than a measurement. The number originally recorded how many times the wire had been pulled through successively smaller dies, so more passes meant a thinner wire and a higher number. When the series ran past its zero it kept going with 1/0, 2/0, 3/0 and 4/0 — spoken as "one aught" and so on — each thicker than the last.
Is the area in NEC Table 8 the same as the area here?
Yes, to the precision the table prints. Table 8 gives 3.31 mm² for 12 AWG and 13.3 mm² for 6 AWG, which are these figures rounded to three significant figures. The table also carries circular mils, stranded diameters and resistance per thousand feet, and those are the columns to use for a voltage-drop calculation rather than the area alone.
Does equal area mean equal ampacity?
No, and this is the single most important thing on the page. Ampacity depends on the insulation's temperature rating, how the cable is installed, the ambient temperature, how many current-carrying conductors share the raceway, and what the terminals at each end are rated for. Two conductors identical in cross-section can have quite different permitted currents under NEC 310.16 and under IEC installation tables, and the two standards do not even define the reference conditions the same way.
What happens above 4/0?
The gauge series stops and North American practice switches to thousands of circular mils — 250 kcmil, 350 kcmil, 500 kcmil and upward. A circular mil is the area of a circle one thousandth of an inch across, so 250 kcmil is about 127 mm². This page covers the gauge range only and says so rather than extrapolating a series that has ended.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.