Convert AWG to diameter, area and resistance.
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How do you convert AWG to wire diameter, area and resistance?
Diameter d = 0.127 × 92^((36 − n) ÷ 39) mm, area = π⁄4 × d², and resistance = resistivity × length ÷ area. A higher AWG number means thinner wire, with more resistance. For example, AWG 12 is about 2.05 mm in diameter and 3.31 mm² in area; 100 m of copper has roughly 0.52 Ω.
Understanding your result
In AWG, a higher number means a thinner wire, and every six-gauge step roughly doubles or halves the cross-sectional area. Thinner wire has more resistance, which causes more voltage drop and heat for the same current.
Formula and method
Diameter d = 0.127 × 92^((36 − n) ⁄ 39) mm. Area = π⁄4 × d². Resistance = resistivity × length ⁄ area.
Assumptions and limitations
Diameter and area come from the standard AWG formula for solid round wire; stranded conductors have a slightly larger overall diameter for the same copper area. Resistance uses nominal resistivity at about 20 degrees Celsius and rises with temperature. It does not cover insulation, ampacity ratings or skin effect at high frequencies.
Worked example
AWG 12 is about 2.05 mm in diameter and 3.31 mm² in area; 100 m of copper has roughly 0.52 Ω.
How to use this tool
- Enter the AWG number.
- Optionally enter a length and material.
- Read the diameter, area and resistance.
Common mistakes to avoid
- Forgetting that a higher AWG number is a thinner wire.
- Using copper resistance figures for aluminium wire.
About the Wire Gauge (AWG) Calculator
The Wire Gauge Calculator converts an American Wire Gauge (AWG) number into the wire’s diameter, cross-sectional area and, for a given length, its resistance in copper or aluminium.
Who should use this tool
Electricians, electronics hobbyists and engineers selecting wire.
Benefits
- Diameter in mm and inches.
- Area in mm² and kcmil.
- Resistance for copper or aluminium.
- Shows the AWG formula.
Practical use cases
- Choosing wire for a circuit.
- Estimating voltage drop over a run.
- Converting AWG to metric sizes.
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Frequently asked questions
Does a higher AWG mean thicker or thinner?
Thinner. The gauge number rises as the wire gets smaller — AWG 12 is thicker than AWG 20.
How is resistance calculated?
Resistance = material resistivity × length ÷ cross-sectional area, assuming a solid round conductor at 20°C.
Does this tool tell me the maximum safe current for a gauge?
No. It converts gauge to diameter, area and resistance, but it does not give ampacity, which is the safe current-carrying capacity. Ampacity depends on insulation type, installation method, bundling and ambient temperature, and is governed by wiring regulations. Always consult the relevant electrical code for current limits.