NEC Circular Mils Table (AWG & kcmil)
Circular-mil (CM / kcmil) area, conductor diameter, and metric mm² for every wire size from 14 AWG to 1000 kcmil, per NEC 2023 Chapter 9, Table 8 (solid copper).
| Size | Diameter (mil) | Area (circular mils) | Area (kcmil) | Area (mm²) |
|---|---|---|---|---|
| 14 AWG | 64.1 | 4,110 | 4.11 | 2.08 |
| 12 AWG | 80.8 | 6,530 | 6.53 | 3.31 |
| 10 AWG | 101.9 | 10,380 | 10.4 | 5.26 |
| 8 AWG | 128.5 | 16,510 | 16.5 | 8.37 |
| 6 AWG | 162.0 | 26,240 | 26.2 | 13.30 |
| 4 AWG | 204.3 | 41,740 | 41.7 | 21.15 |
| 3 AWG | 229.4 | 52,620 | 52.6 | 26.67 |
| 2 AWG | 257.6 | 66,360 | 66.4 | 33.62 |
| 1 AWG | 289.3 | 83,690 | 83.7 | 42.41 |
| 1/0 AWG | 324.9 | 105,600 | 105.6 | 53.49 |
| 2/0 AWG | 364.8 | 133,100 | 133.1 | 67.43 |
| 3/0 AWG | 409.6 | 167,800 | 167.8 | 85.01 |
| 4/0 AWG | 460.0 | 211,600 | 211.6 | 107.20 |
| 250 kcmil | 500.0 | 250,000 | 250.0 | 126.70 |
| 300 kcmil | 547.7 | 300,000 | 300.0 | 152.00 |
| 350 kcmil | 591.6 | 350,000 | 350.0 | 177.40 |
| 400 kcmil | 632.5 | 400,000 | 400.0 | 202.70 |
| 500 kcmil | 707.1 | 500,000 | 500.0 | 253.40 |
| 600 kcmil | 774.6 | 600,000 | 600.0 | 304.00 |
| 700 kcmil | 836.7 | 700,000 | 700.0 | 354.70 |
| 750 kcmil | 866.0 | 750,000 | 750.0 | 380.00 |
| 800 kcmil | 894.4 | 800,000 | 800.0 | 405.40 |
| 900 kcmil | 948.7 | 900,000 | 900.0 | 456.00 |
| 1000 kcmil | 1000.0 | 1,000,000 | 1000.0 | 506.70 |
NEC 2023 · Chapter 9, Table 8 · solid copper · CM = (diameter in mils)²
How to read the circular mils table
Find your wire size in the left column. The circular mils column is the bare copper cross-sectional area used in NEC Chapter 9, Table 8 — the value the code uses for resistance, voltage-drop, and (for the fine-print notes) parallel-conductor rules. For sizes above 4/0 AWG the industry switches from gauge numbers to kcmil (thousands of circular mils): a 250 kcmil conductor is simply 250,000 circular mils.
Circular mils vs square inches vs mm²
These three areas measure different things and are not interchangeable. Circular mils (this table) is the bare conductor metal area. mm² is the metric equivalent of that same copper area (1 CM = 0.0005067 mm²). The square-inch area used for conduit fill is different again — it is the insulated conductor's outside area from NEC Chapter 9, Table 5, which includes the insulation jacket. Never plug a circular-mil value into a conduit-fill calculation.
Why circular mils matter
Ampacity climbs with copper area, so circular mils are the cleanest way to compare conductors and to size parallel sets: two 250 kcmil conductors in parallel give 500,000 CM, matching a single 500 kcmil run for resistance. The measure also drives voltage-drop math — resistance is inversely proportional to circular-mil area. For the insulated dimensions that govern how many wires fit in a raceway, use the EMT fill chart or the live conduit fill calculator instead.
FREQUENTLY ASKED QUESTIONS
What is a circular mil?
What is kcmil?
How do circular mils relate to mm²?
Where does the NEC use circular mils?
Circular-mil and diameter values are transcribed from NEC 2023 (NFPA 70) Chapter 9, Table 8 (solid copper); mm² equivalents are the IEC conversions. WireFillChart is an independent reference, not affiliated with or endorsed by NFPA. Verify against the code edition adopted by your local authority having jurisdiction (AHJ).