Formula
R = ρ20 × L / A × [1 + α20 × (T − 20)]
Worked example
A 100 m copper conductor with 16 mm² cross-section at 20°C: R = 0.01724 × 100 / 16 = 0.10775 Ω. At 70°C, using α = 0.00393/°C, R ≈ 0.12893 Ω.
Cable Resistance Calculator: Copper vs Aluminium
Estimate DC conductor resistance from length, cross-sectional area, material and temperature.
Open interactive calculator →Important limitations
The entered length is conductor length. For a two-wire loop, include the full outgoing and return conductor lengths. DC resistance does not include skin effect, proximity effect, terminations or manufacturing tolerances.
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Educational approximation only. Verify results and applicable standards before electrical installation work.