Resistivity converter
Convert resistivity between SI units, the microhm-centimeters of metallurgy and the %IACS of the cable industry.
That's about the same as copper. A meter of 1 mm² wire made of it would have about 0.01724 Ω of resistance.
What it means
How well does it conduct?
Resistivity rises with temperature for metals and falls for semiconductors. Published values are at 20 °C unless stated otherwise.
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Your resistivity in every unit
Learn
Three things worth knowing
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R = ρL ÷ A
Resistance is resistivity times length divided by area. Double the length and the resistance doubles; double the area and it halves.
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Copper as the yardstick
The International Annealed Copper Standard of 1913 fixed a reference so that wire from any mill could be compared. Modern copper often exceeds 100% IACS, because refining improved.
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%IACS runs backwards
A higher %IACS means lower resistivity. Aluminum at 61% IACS conducts worse than copper at 100%, not better.
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Popular resistivity conversions
Background
About resistivity
Resistivity is the property of the material; resistance is the property of the piece. A meter of 1 mm² copper wire has a resistance of 17 milliohms because copper’s resistivity is 1.72 × 10⁻⁸ Ω·m.
The cable industry uses %IACS instead, where annealed copper is defined as exactly 100% and everything else is measured against it.