Voltage drop on lines

Online calculators and formulas for calculating the voltage loss of a line

Calculate loss voltage of a line

The voltage drop of an electrical line is calculated on this page. To do this, the input voltage, the current, the simple cable length and the cable cross-section must be specified.

A phase shift in the case of inductive loading can be specified as an option. A value of 1 is preset for Cos φ for ohmic load and direct current.

The specific resistance or the conductance can be specified for the material of the conductor. The following table contains the most common values of the conductance.

The specific conductance values of the most common cables are



Copper 56.0
Silver 62.5
Aluminium 35.0

For a list of other specific resistances and conductance values click here.

Online calculators

Applied voltage in V
Current in A.
Single length of line
Cross-section in mm2
Cos φ

Enter one of the two values:

Specific resistance
or conductance

Voltage drop

Useful voltage

Loss of voltage

Line resistance

Decimal places

Formulas for calculation

Calculate the resistance of a conductor

\(\displaystyle R=\frac{ρ · l}{A}\)
\(\displaystyle R=\frac{l}{σ · A}\)

Total resistance of the line

\(\displaystyle R=2 ·\frac{ρ · l}{A}\)
\(\displaystyle R=2 ·\frac{l}{σ · A}\)

Calculate the line voltage drop

\(\displaystyle ΔU=2 ·\frac{l}{σ · A}· I · Cos φ \)

Line voltage loss in %

\(\displaystyle Δu=\frac{ΔU}{Un} ·100 \% \)


\(\displaystyle A \) cross-section

 \(\displaystyle l \)  length

\(\displaystyle R \) Resistance of the line

\(\displaystyle ρ \) Specific resistance

\(\displaystyle σ \)Specific conductance

\(\displaystyle Un \) Nominal voltage (input)

\(\displaystyle ΔU \) Loss voltage