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SWG Converter (BS 3737 legacy UK)
Search the legacy UK Standard Wire Gauge table. SWG is legacy in UK practice; mm² is the modern sizing reference.
Legacy lookup only. SWG values are shown for cross-reference; prefer mm² for current UK specification workflows.
Search by SWG, label, diameter (mm), or area (mm²).
| SWG | Label | Diameter (mm) | Area (mm²) | ≈ AWG |
|---|---|---|---|---|
| -6 | 7/0 | 12.7000 | 126.6769 | -4 |
| -5 | 6/0 | 11.7860 | 109.0995 | 4/0 |
| -4 | 5/0 | 10.9730 | 94.5672 | 3/0 |
| -3 | 4/0 | 10.1600 | 81.0732 | 3/0 |
| -2 | 3/0 | 9.4490 | 70.1232 | 2/0 |
| -1 | 2/0 | 8.8390 | 61.3615 | 2/0 |
| 0 | 1/0 | 8.2300 | 53.1973 | 1/0 |
| 1 | 1 | 7.6200 | 45.6037 | 1 |
| 2 | 2 | 7.0100 | 38.5945 | 1 |
| 3 | 3 | 6.4010 | 32.1800 | 2 |
| 4 | 4 | 5.8930 | 27.2749 | 3 |
| 5 | 5 | 5.3850 | 22.7752 | 4 |
| 6 | 6 | 4.8770 | 18.6808 | 5 |
| 7 | 7 | 4.4700 | 15.6930 | 5 |
| 8 | 8 | 4.0640 | 12.9717 | 6 |
| 9 | 9 | 3.6580 | 10.5094 | 7 |
| 10 | 10 | 3.2510 | 8.3009 | 8 |
| 11 | 11 | 2.9460 | 6.8164 | 9 |
| 12 | 12 | 2.6420 | 5.4822 | 10 |
| 13 | 13 | 2.3370 | 4.2895 | 11 |
| 14 | 14 | 2.0320 | 3.2429 | 12 |
| 15 | 15 | 1.8290 | 2.6273 | 13 |
| 16 | 16 | 1.6260 | 2.0765 | 14 |
| 17 | 17 | 1.4220 | 1.5881 | 15 |
| 18 | 18 | 1.2190 | 1.1671 | 16 |
| 19 | 19 | 1.0160 | 0.8107 | 18 |
| 20 | 20 | 0.9140 | 0.6561 | 19 |
| 21 | 21 | 0.8130 | 0.5191 | 20 |
| 22 | 22 | 0.7110 | 0.3970 | 21 |
| 23 | 23 | 0.6100 | 0.2922 | 22 |
| 24 | 24 | 0.5590 | 0.2454 | 23 |
| 25 | 25 | 0.5080 | 0.2027 | 24 |
| 26 | 26 | 0.4570 | 0.1640 | 25 |
| 27 | 27 | 0.4170 | 0.1366 | 26 |
| 28 | 28 | 0.3760 | 0.1110 | 27 |
| 29 | 29 | 0.3450 | 0.0935 | 27 |
| 30 | 30 | 0.3150 | 0.0779 | 28 |
| 31 | 31 | 0.2950 | 0.0683 | 29 |
| 32 | 32 | 0.2740 | 0.0590 | 29 |
| 33 | 33 | 0.2540 | 0.0507 | 30 |
| 34 | 34 | 0.2340 | 0.0430 | 31 |
| 35 | 35 | 0.2130 | 0.0356 | 32 |
| 36 | 36 | 0.1930 | 0.0293 | 32 |
| 37 | 37 | 0.1730 | 0.0235 | 33 |
| 38 | 38 | 0.1520 | 0.0181 | 34 |
| 39 | 39 | 0.1320 | 0.0137 | 36 |
| 40 | 40 | 0.1220 | 0.0117 | 36 |
| 41 | 41 | 0.1120 | 0.0099 | 37 |
| 42 | 42 | 0.1020 | 0.0082 | 38 |
| 43 | 43 | 0.0914 | 0.0066 | 39 |
| 44 | 44 | 0.0813 | 0.0052 | 40 |
| 45 | 45 | 0.0711 | 0.0040 | 41 |
| 46 | 46 | 0.0610 | 0.0029 | 42 |
| 47 | 47 | 0.0508 | 0.0020 | 44 |
| 48 | 48 | 0.0406 | 0.0013 | 46 |
| 49 | 49 | 0.0305 | 0.0007 | 48 |
| 50 | 50 | 0.0254 | 0.0005 | 50 |
How it's calculated
SWG values are looked up from the static BS 3737 dataset in src/data/swg-table.json. No interpolation is performed.
Area and nearest AWG are derived from diameter using the shared engine conversion helpers so all tools use one calculation path.
Why SWG is legacy in the UK
SWG is retained mainly for historical drawings and imported specs. Modern UK cable sizing and procurement workflows are metric-first in mm².
Continue with AWG ↔ mm² converter and review sources and standards framing.