Wire Gauge (AWG) Converter
Convert an American Wire Gauge number into everything it implies: diameter, radius, cross-sectional area in mm² and circular mils, and the standard resistance of a copper conductor of that size. AWG is defined by a geometric formula, not a lookup table, so this tool computes each value exactly for any gauge — including the 0, 00, 000 and 0000 sizes. Remember that a larger gauge number means a thinner wire, and every six gauges roughly doubles the diameter.
How to use this tool
- Enter an AWG gauge number — a whole number, or 0, 00, 000, 0000 for the large sizes.
- Read the diameter, radius, area, circular mils and copper resistance.
- Use the area (mm²) to compare with metric cable sizes.
- Use the resistance per kilometre for voltage-drop estimates.
- Remember: bigger gauge number = thinner wire; each 3 gauges roughly doubles the area.
The formula
American Wire Gauge is defined geometrically, not by a table. Gauge 36 is 0.005 inch and gauge 0000 is 0.46 inch; every gauge between is a geometric step, so diameter, area and resistance follow from a formula.
diameter_in = 0.005 × 92^((36 − n) ÷ 39)
area = π · (diameter ÷ 2)²
circular_mils = (diameter_in × 1000)²
R = ρ · length ÷ area- n
- Gauge number (0000 = −3 … 40)
- circular mil
- Area of a 0.001-inch circle; wire = (mils)²
- ρ
- Copper resistivity, 1.68×10⁻⁸ Ω·m at 20 °C
Each 3-gauge decrease roughly doubles the cross-sectional area, and each 6-gauge decrease roughly doubles the diameter — a direct consequence of the 92-based ratio.
Worked examples
Common house wire
- Given
- AWG 12
- Result
- ≈ 2.05 mm, 3.31 mm²
AWG 12 is about 2.05 mm in diameter and 3.31 mm² in area — a common size for power circuits.
The largest gauge
- Given
- AWG 0000 (4/0)
- Result
- ≈ 11.68 mm
The largest standard AWG size, written 0000 or 4/0, is 0.46 inch — about 11.68 mm — for heavy feeders.
Doubling rule
- Given
- AWG 10 vs AWG 16
- Result
- About double the diameter
Six gauges of difference roughly doubles the diameter, a direct result of the 92-based geometric definition.
Frequently asked questions
The numbering comes from the old drawing process, where wire was pulled through successively smaller dies; the gauge counts the drawing steps. More steps means more stretching and a thinner wire, so the count runs backwards from size — AWG 30 is much thinner than AWG 10.
Geometrically. Gauge 36 is exactly 0.005 inch and gauge 0000 is exactly 0.46 inch; every gauge between is a fixed geometric ratio, diameter = 0.005 × 92^((36−n)/39). Because it is a formula, this tool computes exact values for any gauge rather than reading a table.
A circular mil is the area of a circle one mil (0.001 inch) in diameter. Conveniently, a round wire’s area in circular mils is just its diameter in mils, squared. It is the traditional US unit for wire cross-section; 1000 circular mils is one kcmil, used for large cables.
The geometry is exact; the resistance uses a reference copper resistivity of 1.68×10⁻⁸ Ω·m at 20 °C. Real resistance varies with the copper’s purity and temper and rises with temperature, and aluminium conductors have about 1.6 times the resistance. Treat the resistance as a standard reference figure.
The tool gives the cross-sectional area directly in mm². It is not a round-number conversion — AWG 12 is 3.31 mm², close to but not exactly the 2.5 or 4 mm² metric sizes — so match by area and required current capacity rather than assuming a one-to-one equivalence.
Related tools
Convert electrical units (volts, amps, ohms, farads and more) and radiation units (gray, sievert, becquerel, curie).
Screw, Bolt & Thread CalculatorCalculate thread geometry — pitch and minor diameter — for metric and Unified threads.
Structural Steel & Lumber Weight CalculatorEstimate the weight of steel profiles and lumber from dimensions and reference densities.