Conductor Resistance from Resistivity Calculator
Estimate the resistance of a uniform conductor from material resistivity, conductor length and cross-sectional area. The input area is in square millimetres and is converted to square metres in the formula.
How to use this calculator
- Enter resistivity in Ω·m, length in metres and conductor cross-sectional area in mm². Keep the material coefficient appropriate to the application.
- Check the labels and units before applying the result to a real task.
- Change one input at a time when comparing scenarios.
Formula and method
R = ρL/A; 1 mm² = 10⁻⁶ m²
- R = ρL/A; 1 mm² = 10⁻⁶ m²
- The model excludes temperature rise, contact resistance, skin effect, alloy variation and installation conditions.
Worked examples
Worked example
A 10 m copper-like conductor uses ρ = 1.68×10⁻⁸ Ω·m and area 1.5 mm².
R = 1.68×10⁻⁸×10/(1.5×10⁻⁶) ≈ 0.112 Ω.
R = 1.68×10⁻⁸×10/(1.5×10⁻⁶) ≈ 0.112 Ω.
Understanding the result
Estimate the resistance of a uniform conductor from material resistivity, conductor length and cross-sectional area. The input area is in square millimetres and is converted to square metres in the formula.
The model excludes temperature rise, contact resistance, skin effect, alloy variation and installation conditions.
Important notes
The model excludes temperature rise, contact resistance, skin effect, alloy variation and installation conditions.
Displayed values are rounded for readability; retain appropriate precision when continuing a calculation.
Frequently asked questions
What is resistivity?
Resistivity is a material property describing how strongly the material resists electrical current, independent of a particular conductor shape.
Why does a longer conductor have more resistance?
The formula is proportional to length: a longer uniform conductor gives current a longer path through the material.
Does a real wire keep the same resistance at every temperature?
No. Resistivity commonly varies with temperature and material. Use a suitable coefficient for the operating conditions.
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Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.