Wire Resistivity & Conductivity Calculator

Electrical resistivity, usually written as rho or ρ, is a material property that describes how strongly a material opposes current flow. Its SI unit is Ω·m.

Electrical conductivity, usually written as sigma or σ, is the reciprocal of resistivity. Its SI unit is S/m.

Resistance is the Ω value of a specific conductor or object. Resistivity is a material property in Ω·m and does not by itself include length or area.

Conductivity is a material property in S/m. Conductance is the reciprocal of a particular resistance and uses the unit S.

For a uniform conductor, resistivity can be inferred with ρ = RA/L, where R is measured resistance, A is conductive area, and L is conductor length.

Conductivity is σ = 1/ρ. From geometry and measured resistance, σ = L/(RA).

They are reciprocals in SI units, so ρ × σ = 1 when ρ is in Ω·m and σ is in S/m.

Common resistivity units include Ω·m, Ω·mm²/m, µΩ·cm, and nΩ·m.

Common conductivity units include S/m, kS/m, and MS/m.

Ohm-meter, written Ω·m, is resistance multiplied by length. It is a material property unit, not the same as ohms.

S/m means siemens per meter. It is the SI unit of electrical conductivity, not simple conductance.

Convert resistivity to Ω·m first, then use σ = 1/ρ. The calculator can display the result in S/m, kS/m, or MS/m.

Convert conductivity to S/m first, then use ρ = 1/σ.

Use R = ρL/A, where L is the measured conductor length and A is the conductive cross-sectional area.

Use ρ = RA/L with measured resistance, conductor area, and actual conductor length.

For the same material, doubling length doubles resistance, and doubling conductive area halves resistance.

No. Length changes the conductor resistance, not the material resistivity.

No. Diameter and area change resistance for a specific conductor, but they do not change the material resistivity.

Use R/L = ρ/A. For copper at 1.724e-8 Ω·m and 2.5 mm² area, the result is 0.006896 Ω/m.

This project currently uses the shared copper reference value 1.724e-8 Ω·m at approximately 20 °C. Real copper varies with temperature, purity, alloy, and manufacturing condition.

Metal resistivity changes with temperature because electron scattering changes. This calculator uses reference-temperature values and does not apply temperature correction.

This project currently uses the shared aluminum reference value 2.82e-8 Ω·m from the AWG material dataset.

Yes. Wire resistance and measured-resistivity modes can use AWG, reusing the shared raw AWG conductive area data.

No. Contact resistance, probe resistance, lead resistance, and connector resistance are not automatically subtracted.

For low-ohm conductors, contact and lead resistance can be comparable to conductor resistance, causing the inferred resistivity to appear too high.

A four-wire measurement separates current leads from voltage-sense leads, reducing the effect of probe and lead resistance in low-resistance measurements.

No. Temperature correction belongs to the planned Wire Resistance vs Temperature Calculator, WIR-011.