Step-by-step method
- Always check units, prefixes and order of magnitude.
- Convert AWG to diameter and area and estimate resistance, voltage drop and an indicative current range.
- Compare the result with temperature, tolerances and real conditions.
AWG wire size and current
Convert AWG to diameter and area and estimate resistance, voltage drop and an indicative current range.
Calculate
Diameter
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Copper area
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Resistance
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Round-trip drop
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Indicative current
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Mistakes to avoid
- Always check units, prefixes and order of magnitude.
- Do not use an ideal result without margin or a datasheet check.
- Compare the result with temperature, tolerances and real conditions.
Component selection
For installations, select cable from applicable code tables and manufacturer ratings, not diameter alone.
Worked example
AWG 18 is about 1.02 mm in diameter, 0.823 mm² and roughly 21 mΩ/m at 20 °C.
Limits and safety
The current range is only a 5–10 A/mm² comparison; insulation, bundling, temperature and codes take precedence.
Technical sources
Do not use an ideal result without margin or a datasheet check.