Conductor Resistance Calculator
Calculate resistance, current density and heating for a conductor at a given load.
About Conductor Resistance Calculator
Loss rises with the square of current, so a conductor at twice the current dissipates four times the heat. Current density around 3 to 5 A/mm² is typical for insulated copper in free air. Because loss scales with I², going one cable size larger often pays for itself in reduced energy loss over the installation’s life.
Formula
Conductor Resistance
R = ρ L ÷ A; loss = I² R; current density = I ÷ A
- current density
- Amps per square millimetre, the practical measure of conductor loading
Worked example
With the default values below, Conductor Resistance Calculator returns Conductor Resistance of 0.10775. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Conductor cross-sectional areaminimum 0.01 mm2
- 16 mm2
- Conductor lengthminimum 0 m
- 100 m
- Current carriedminimum 0 A
- 60 A
- Conductor materialone of Copper, Aluminium
- Copper
Results
- Conductor Resistance
- 0.10775 ohm
- Power Lost as Heat
- 387.900 W
- Current Density
- 3.750 A/mm2
- Voltage Drop One Way
- 6.4650 V
- Annual Energy Lost at Continuous Duty
- 3,398.00 kWh
Step by step
- 1Values used
- 2Conductor Resistance
- 3Conductor Resistance= 0.10775 ohm
- 4Power Lost as Heat= 387.900 W
- 5Current Density= 3.750 A/mm2
- 6Voltage Drop One Way= 6.4650 V
- 7Annual Energy Lost at Continuous Duty= 3,398.00 kWh
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Conductor Resistance calculated?
R = ρ L ÷ A; loss = I² R; current density = I ÷ A Loss rises with the square of current, so a conductor at twice the current dissipates four times the heat. Current density around 3 to 5 A/mm² is typical for insulated copper in free air.
Why does Conductor Resistance matter?
Because loss scales with I², going one cable size larger often pays for itself in reduced energy loss over the installation’s life.
What values do I need to enter?
This calculator takes 4 inputs: Conductor cross-sectional area, Conductor length, Current carried, Conductor material. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.