Wire Gauge Calculator (AWG)
Look up the full specification of any AWG wire gauge - diameter in inches and millimetres, cross-sectional area in circular mils and mm², DC resistance, and NEC Table 310.16 ampacity at 60 °C, 75 °C and 90 °C. A quick reference for copper and aluminium conductors.
Diameter
2.05mm
Diameter
0.0808in
Area
3.31mm²
Area
6,530cmil
DC resistance
1.588Ω/1000ft
Ampacity @ 60 °C
20A
Ampacity @ 75 °C
25A
Ampacity @ 90 °C
30A
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Reading the AWG system
American Wire Gauge is logarithmic: every six gauges the diameter roughly halves, and every three gauges the cross-sectional area roughly halves. That is why jumping from 14 AWG to 8 AWG dramatically increases current capacity.
For power circuits, the ampacity columns above come from NEC Table 310.16. For data, control or automotive wiring, the diameter and resistance figures are usually what matter most.
Common gauges at a glance
- 14 AWG - 15 A lighting circuits.
- 12 AWG - 20 A general receptacle circuits.
- 10 AWG - 30 A water heaters, dryers.
- 6 AWG - 55–65 A ranges and sub-feeds.
Frequently Asked Questions
- What does AWG mean?
- AWG stands for American Wire Gauge. It is a standardised system where a smaller number means a larger conductor - 6 AWG is much thicker than 14 AWG. Each three-gauge step roughly doubles the cross-sectional area.
- How is wire diameter related to AWG?
- Diameter (inches) = 0.005 × 92^((36 − n) ÷ 39), where n is the gauge number. Sizes above 1 AWG are written 1/0 (one-aught) through 4/0, with 4/0 being the largest AWG size before kcmil.
- Why does resistance matter when choosing a gauge?
- DC resistance per 1000 feet determines both heating and voltage drop. A larger gauge has lower resistance, carrying more current with less loss - important on long runs.
- Is copper or aluminium better for a given gauge?
- Copper has lower resistance for the same gauge, so it carries more current. Aluminium is lighter and cheaper but needs to be one or two sizes larger to match copper's ampacity.
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