Voltage Drop Calculator
ΔV = circuit factor × I × L × resistivity / conductor area.
Inputs and units
- Supply voltage (V): Enter your value in the format and unit shown.
- Current (A): Enter your value in the format and unit shown.
- One-way cable length (m): Enter your value in the format and unit shown.
- Conductor cross-section (mm²): Enter your value in the format and unit shown.
- Conductor: Choose Copper, Aluminium.
- Circuit: Choose DC / single-phase resistive load, Three-phase resistive load.
Calculation method
ΔV = circuit factor × I × L × resistivity / conductor area.
Worked example
The example values are: Supply voltage (V) = 230; Current (A) = 10; One-way cable length (m) = 20; Conductor cross-section (mm²) = 2.5; Conductor = copper; Circuit = dc
- Voltage drop (V): 2.75856
- Voltage drop (%): 1.199373913
- Load voltage estimate (V): 227.24144
Assumptions and limitations
Resistivity at approximately 20°C; neglects reactance, power-factor effects, joints and heating. This does not establish cable ampacity or code compliance.
Using your result
Select Calculate after changing inputs. Copy result copies the displayed output; Download result saves a text file. Reset returns the form to its example inputs. Calculations run in your browser.
Voltage Drop Calculator FAQs
What method does this calculator use?
ΔV = circuit factor × I × L × resistivity / conductor area.
What should I check before using the result?
Resistivity at approximately 20°C; neglects reactance, power-factor effects, joints and heating. This does not establish cable ampacity or code compliance.