AWG to mm² Converter
AWG, mm², diameter, and approximate ampacity — for reference.
How to use
Type a value in either field and the other updates. AWG accepts whole numbers and 1/0, 2/0, 3/0, 4/0 for the larger gauges.
- Enter an AWG size to get its mm², OR enter an mm² value to get the closest AWG.
- The reference table below shows common gauges with their diameter and approximate 75 °C ampacity (NEC Table 310.16).
- Use this for unit reference and quick lookup. Installation decisions belong to a licensed electrician working from local code.
- Larger AWG numbers mean smaller wire. 0 (1/0) is bigger than 1; 4/0 (0000) is the largest standard gauge.
Reviewed 3 June 2026 · methodology cited
About this converter
The American Wire Gauge (AWG) is the US and Canadian system for sizing electrical conductors. The metric system uses cross-sectional area in square millimetres (mm²). This converter handles both directions: enter an AWG number to get the metric equivalent, or enter an mm² value to find the closest AWG.
The reference table below the converter lists common gauges from 4/0 (the largest standard size, ≈107 mm²) down to 14 AWG (the smallest commonly used for general-purpose 15 A residential circuits, ≈2.08 mm²), along with conductor diameter and approximate ampacity at 75 °C for copper and aluminum at no more than three current-carrying conductors per raceway.
How AWG works
The AWG diameter formula is d(mm) = 0.127 × 92^((36 − n) ÷ 39), where n is the AWG number. For sizes larger than 0 — written 1/0 (n=0), 2/0 (n=−1), 3/0 (n=−2), and 4/0 (n=−3) — the same formula applies with a negative n. Cross-sectional area is then π × (d ÷ 2)². The converter computes both, and the "closest AWG" function for mm² input picks the gauge whose area is nearest to the value you typed.
Ampacity figures shown in the reference table follow the NEC Table 310.16 column for 75 °C insulation (THWN, USE, RHW), at not more than three current-carrying conductors in a raceway, for ambient temperatures up to 30 °C. Aluminum ampacity is lower than copper at the same gauge because aluminum has higher resistance per cross-section.
Common wire gauges
| AWG | mm² | Ø mm | Cu 75 °C (A) | Al 75 °C (A) |
|---|---|---|---|---|
| 4/0 | 107.2 | 11.68 | 230 | 180 |
| 3/0 | 85.0 | 10.40 | 200 | 155 |
| 2/0 | 67.4 | 9.27 | 175 | 135 |
| 1/0 | 53.5 | 8.25 | 150 | 120 |
| 1 | 42.4 | 7.35 | 130 | 100 |
| 2 | 33.6 | 6.54 | 115 | 90 |
| 4 | 21.2 | 5.19 | 85 | 65 |
| 6 | 13.3 | 4.11 | 65 | 50 |
| 8 | 8.37 | 3.26 | 50 | 40 |
| 10 | 5.26 | 2.59 | 35 | 30 |
| 12 | 3.31 | 2.05 | 25 | 20 |
| 14 | 2.08 | 1.63 | 20 | 15 |
Reference notes
Cable size by region: North American residential 15 A circuits typically use 14 AWG copper, 20 A use 12 AWG, 30 A use 10 AWG. European installations use 1.5 mm², 2.5 mm², and 4 mm² for the same loads. Aluminum is one gauge larger than copper for the same ampacity — a 60 A copper feeder is 6 AWG, but the aluminum equivalent is 4 AWG.
Voltage drop matters more than ampacity over long runs. The NEC recommends keeping total voltage drop under 5 percent (3 percent on the branch circuit). For a 120 V circuit that is 6 V drop maximum; for 240 V, 12 V. Always derate ampacity for ambient temperature above 30 °C and for more than three current-carrying conductors per raceway — the corrections live in NEC Table 310.15(B). And again: actual sizing for an installation is your electrician's call, not a calculator's.
Frequently asked questions
Why does a smaller AWG number mean a bigger wire?
AWG was originally defined by the number of drawing-die passes needed to reduce a rod to that diameter — more passes = smaller wire = higher AWG number. So 14 AWG (many passes) is smaller than 10 AWG (fewer passes). The same convention extends past zero with 1/0, 2/0, 3/0, 4/0 for progressively larger conductors.
What does 1/0 (one-aught) mean?
1/0 (sometimes written 0 AWG, read "one aught") is the next size up from 1 AWG. The sequence continues 2/0 (00), 3/0 (000), and 4/0 (0000), which is the largest standard AWG size. Anything larger is measured directly in cubic-mil units (MCM or kcmil) rather than gauge numbers.
Can I use this for sizing my own circuit?
No. This is a reference utility for unit conversion and quick lookup. Sizing a real circuit involves the load, the length of run, the ambient temperature, the number of current-carrying conductors in the raceway, voltage drop, the wire insulation type, and your local electrical code — all of which require a licensed electrician.
Why is aluminum ampacity lower than copper at the same gauge?
Aluminum has about 60 percent of the conductivity of copper by volume. For the same cross-sectional area it carries roughly 80 percent of the current copper can — that is why aluminum service drops are typically one to two AWG sizes larger than the copper equivalent for the same ampacity.
Are the ampacity numbers in the table NEC compliant?
They reflect NEC Table 310.16 at 75 °C insulation rating (THWN, USE, RHW), three or fewer current-carrying conductors per raceway, 30 °C ambient. They are reference figures only — your installation may need correction factors for ambient temperature, conduit fill, continuous loads, or service entrance derating. Always confirm against the NEC edition adopted by your jurisdiction.
Does this work for Canadian Electrical Code installations?
The AWG-to-mm² math is universal — gauges and areas do not change at the border. Ampacity tables in the Canadian Electrical Code (CSA C22.1) are similar but not identical to the NEC. For a Canadian installation, consult the CEC ampacity tables for your specific conductor type and installation method, not the values shown here.