Convert AWG, mm², kcmil, calculate voltage drop, conduit fill, cable ampacity and more.
Pick a topic and open the right calculator in one click.
Wire size cross-reference from AWG to mm² and mm² to AWG.
Symmetrical components, voltage drop and line calculations.
Cable sizing, installation methods and voltage drop checks.
Complex numbers, phasors and rectangular↔polar conversions.
The most-used tools in AWGtomm2.
Convert American Wire Gauge (AWG) to mm² cross-section and mm² back to AWG instantly, with diameter, resistance per km and standard IEC / NEC reference sizes.
Voltage drop calculator with a single page covering BOTH IEC 60364-5-52 Annex G (metric mm² cables, A/B limits) and NEC NFPA 70 Chapter 9 Tables 8–9 (AWG / kcmil, 3% branch / 5% feeder FPNs). Copper / aluminium, 1-phase / 3-phase / DC, temperature correction, parallel conductors, conduit material (NEC), reactance X and ampacity cross-check.
Compute positive, negative and zero sequence components from three-phase currents or voltages (balanced or unbalanced), then reconstruct phase phasors back.
Add, subtract, multiply and divide complex numbers in rectangular and polar forms, with phasor angle in degrees, ideal for power systems and AC circuits.
Estimate the minimum cable cross-section for LV installations using load current, installation method, number of circuits, ambient temperature and voltage drop constraints.
Cable pulling tension calculator and sidewall pressure (SWBP) solver using the AEIC CG5 (2nd Ed.) pulling-guide method. Build the duct run section by section, walk the tension through, calculate SWBP at every bend, and check the pull in both directions.
Full IEC 60364-5-52 cable derating calculator: 12 reference installation methods, ambient/ground temperature correction, soil resistivity, grouping factors for trays/bunched/buried ducts, Annex D curve-fit base ampacities (PVC / XLPE, Cu / Al, 2 or 3 loaded), harmonic derating per Annex E, smallest mm² cross-section and nearest AWG equivalent, with the full factor chain and printable copy.
Five deep dives by a working engineer: how AWG sizes are derived, why they never match metric cable, what the four conductor classes actually mean, and how circular mils, diameter and cross-section relate.
What circular mils are, why the unit exists (to cancel pi in round-conductor area math), how to convert cmil to mm², and the difference between kcmil and the older MCM label on North American cables.
12 AWG converts to 3.31 mm² but you cannot buy a 3.31 mm² cable. Why the two systems are fundamentally different, how to round safely, and which four gauge sizes genuinely pass a metric resistance limit.
IEC 60228 Classes 1 (solid), 2 (stranded), 5 and 6 (flexible) — what the class number actually means, when to use each one, the minimum wire counts, and how stranded resistance limits vary with class.
Why 12 AWG has both a 2.05 mm diameter AND a 3.31 mm² label — which one to use for ferrules/glands vs cable sizing vs purchase orders, and the stranded-wire trap that catches everyone.
The geometric series behind AWG — the two fixed points (4/0 = 460 mils, 36 AWG = 5 mils), the 1.1229 step ratio, formula to compute any gauge, and the 3-6-10 shortcuts for on-site estimation.
Copper wire strands come in counts of 7, 19, 37, 61 and 91 for a reason. What decides the number, what stranding costs in diameter, and how to read a stranded-conductor datasheet.
SWG to mm for every gauge from 7/0 to 40, with the cross-section in mm2. SWG and AWG are different systems, and the same number means a different wire.
kcmil to mm2 for every standard size from 250 to 2000 kcmil, with the exact cross-section, the IEC 60228 size to specify and the equivalent conductor diameter.
IEC 60228:2023 sets the metric conductor sizes, the four classes and the resistance limits every cable is tested against. What is in edition 4 and what changed.
Sixteen size-by-size reference pages: solid diameter, mm² cross-section, kcmil, stranded and flexible class ranges, IEC resistance limits, ampacity and the closest metric cable replacement.
1/0 AWG in mm is 8.25 mm across, with a cross-section of 53.5 mm². Rounding up costs 31% more copper here, and the size below meets the resistance limit.
10 gauge wire in mm is 2.59 mm across, with a cross-section of 5.26 mm2. Here is the metric size to order, the ampacity, and why 30 A caps it regardless.
12 gauge wire in mm is 2.05 mm across, with a cross-section of 3.31 mm2. Here is the metric cable that replaces it, and why 12 AWG fails a 4 mm2 spec.
14 gauge wire in mm is 1.63 mm across, with a cross-section of 2.08 mm2. Here is the metric cable to order and the 28% gap if you round the wrong way.
16 gauge wire in mm is 1.29 mm across for solid wire. Here is the diameter, the metric size that replaces it, and why stranded 16 AWG measures much wider.
18 gauge wire in mm is 1.02 mm across, with a cross-section of 0.823 mm2. It sits closer to a metric size than any other gauge, and that changes the choice.
2/0 AWG in mm is 9.26 mm across, with a cross-section of 67.4 mm2. It is one of only two gauges that meets the resistance limit of the metric size above it.
2 gauge wire in mm is 6.54 mm across, with a cross-section of 33.6 mm2. It is one of only two gauges that actually meets its metric cable resistance limit.
20 gauge wire in mm is 0.813 mm across, with a cross-section of 0.519 mm2. This is the one gauge where rounding down to the smaller metric size is correct.
24 gauge wire in mm is 0.511 mm across, with a cross-section of 0.205 mm2. The nearest metric size is more than double, so there is no real equivalent.
26 gauge wire in mm is 0.404 mm across, with a cross-section of 0.128 mm2. The smallest metric size is almost four times larger, so there is no equivalent.
3/0 AWG in mm is 10.404 mm across, with a cross-section of 85 mm2. Here is the metric size to order, the ampacity, and how to read the 0-series numbering.
4/0 AWG in mm is 11.684 mm across, with a cross-section of 107.2 mm2. Here is the metric size, the ampacity, and why the lug diameter is the number that bites.
4 gauge wire in mm is 5.19 mm across, with a cross-section of 21.1 mm2. Here is the metric size to order, the ampacity, and where the two standards disagree.
6 gauge wire in mm is 4.11 mm across, with a cross-section of 13.3 mm2. Here is the metric size to order, the ampacity, and how fast grouping erodes it.
8 gauge wire in mm is 3.26 mm across, with a cross-section of 8.37 mm2. Here is the metric size to order, the ampacity, and the 28% cost of rounding down.
No. AWG is the American Wire Gauge scale used in North America; mm² is the cross-section in square millimetres used in IEC countries. AWGtomm2 converts both directions with the standard formula.
Yes — our voltage drop calculator supports DC, single-phase AC and three-phase AC, with configurable material (copper/aluminium), power factor and temperature.
Yes. All tools on AWGtomm2 are 100% free and run directly in your browser. No login, no installation.
You can use them as a first-pass estimate. Always confirm with the applicable local standards (NEC, IEC, NF C 15-100, DIN VDE, etc.) and qualified engineering judgment.
