AWG Calculator
Convert AWG and kcmil conductor sizes to mm² and back, using the published areas from NEC Chapter 9, Table 8. 18 AWG through 2000 kcmil. Includes the IEC 60228 metric cross-reference with the equal-or-larger substitution called out explicitly.
How to use this calculator
- Pick the conversion direction: AWG/kcmil → mm², or mm² → AWG/kcmil.
- Select the conductor size (or enter a metric cross-section. The dropdown pre-fills IEC 60228 standard sizes).
- Read the published Table 8 areas in circular mils, kcmil, and mm².
- For metric-to-AWG, use the "smallest AWG ≥ input area" result for substitution. It is the size that never reduces the conductor cross-section. The nearest-by-area size is shown for reference and may be smaller than your input.
NEC reference
Areas are the published values from NEC 2020 Chapter 9, Table 8 (Conductor Properties). Both the circular-mil and mm² columns. These values are unchanged across the 2017, 2020, and 2023 editions. IEC 60228 nominal cross-sections are an international cable standard, not NEC data; the cross-reference is informational. This tool converts area only. It makes no ampacity determination (see the FAQ below).
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
AWG to mm² conversion chart (NEC Chapter 9, Table 8)
Full published conversion table, 18 AWG through 2000 kcmil. The mm² column is the NEC-published figure, not a recomputed approximation.
| Size | Circular mils | mm² |
|---|---|---|
| 18 AWG | 1,620 | 0.823 |
| 16 AWG | 2,580 | 1.31 |
| 14 AWG | 4,110 | 2.08 |
| 12 AWG | 6,530 | 3.31 |
| 10 AWG | 10,380 | 5.261 |
| 8 AWG | 16,510 | 8.367 |
| 6 AWG | 26,240 | 13.3 |
| 4 AWG | 41,740 | 21.15 |
| 3 AWG | 52,620 | 26.67 |
| 2 AWG | 66,360 | 33.62 |
| 1 AWG | 83,690 | 42.41 |
| 1/0 AWG | 105,600 | 53.49 |
| 2/0 AWG | 133,100 | 67.43 |
| 3/0 AWG | 167,800 | 85.01 |
| 4/0 AWG | 211,600 | 107.2 |
| 250 kcmil | 250,000 | 127 |
| 300 kcmil | 300,000 | 152 |
| 350 kcmil | 350,000 | 177 |
| 400 kcmil | 400,000 | 203 |
| 500 kcmil | 500,000 | 253 |
| 600 kcmil | 600,000 | 304 |
| 700 kcmil | 700,000 | 355 |
| 750 kcmil | 750,000 | 380 |
| 800 kcmil | 800,000 | 405 |
| 900 kcmil | 900,000 | 456 |
| 1000 kcmil | 1,000,000 | 507 |
| 1250 kcmil | 1,250,000 | 633 |
| 1500 kcmil | 1,500,000 | 760 |
| 1750 kcmil | 1,750,000 | 887 |
| 2000 kcmil | 2,000,000 | 1013 |
Source: NEC 2020 Chapter 9, Table 8 (Conductor Properties). Identity: 1 cmil = 5.067 × 10⁻⁴ mm².
AWG vs IEC 60228 quick reference
Common substitution pairs, safe direction only (metric size shown is equal to or larger than the AWG conductor it replaces, and vice versa). Area equivalence does not establish ampacity equivalence. The governing code's ampacity table still applies.
| AWG (mm²) | IEC size that is equal or larger |
|---|---|
| 14 AWG (2.08) | 2.5 mm² |
| 12 AWG (3.31) | 4 mm² |
| 10 AWG (5.261) | 6 mm² |
| 8 AWG (8.367) | 10 mm² |
| 6 AWG (13.30) | 16 mm² |
| 4 AWG (21.15) | 25 mm² |
| 2 AWG (33.62) | 35 mm² |
| 1/0 AWG (53.49) | 70 mm² |
| 4/0 AWG (107.2) | 120 mm² |
Frequently asked questions
What is 12 AWG in mm²?
12 AWG is 3.31 mm² (6,530 circular mils) per NEC Chapter 9, Table 8. The nearest IEC 60228 size is 4 mm². About 21% larger. For substitution, 4 mm² replaces 12 AWG in the safe direction; 2.5 mm² is smaller than 12 AWG and is not an equivalent.
How do you convert AWG to mm²?
Read the area directly from NEC Chapter 9, Table 8, which publishes both columns. The identity behind the table is 1 circular mil = 5.067 × 10⁻⁴ mm² (the area of a 0.001-inch-diameter circle). For kcmil sizes: mm² = kcmil × 0.5067. Worked example: 4/0 AWG = 211,600 cmil; 211,600 × 0.0005067 ≈ 107.2 mm². Matching the published value.
Is 2.5 mm² equivalent to 14 AWG?
No. 2.5 mm² (2.5) is larger than 14 AWG (2.08 mm²) and smaller than 12 AWG (3.31 mm²). Replacing 2.5 mm² cable with 14 AWG reduces the copper cross-section by roughly 17%. The wrong direction. The equal-or-larger substitution for 2.5 mm² is 12 AWG.
Why do published mm² values differ slightly from cmil × 0.0005067?
For small AWG sizes the NEC converts from the exact AWG-defined conductor diameter rather than the rounded circular-mil figure, so the published mm² can differ in the third digit (18 AWG: 1,620 cmil × 0.0005067 = 0.821 mm², published 0.823 mm²). This tool reports the published Table 8 values.
Does area equivalence mean ampacity equivalence?
No. NEC ampacity comes from Table 310.16 (or the table for the applicable wiring method) under NEC assumptions; IEC 60228 conductors are rated under IEC 60364-5-52 with different ambient bases and installation methods. Use this tool for the area conversion, then verify ampacity under the code governing the installation. The Wire Ampacity Calculator handles the NEC side.
Related calculators
- Wire Ampacity Calculator: Derated NEC ampacity for a specific conductor size.
- Wire Gauge Calculator: Minimum AWG for a required ampacity with full derating.
- Wire Size Calculator: Sizes for ampacity and voltage drop together.
- Voltage Drop Calculator: Check the run length against the NEC 3%/5% recommendations.
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