FREE · CALCULATORS & CONVERTERS
Voltage Drop Calculator.
Estimate resistive voltage drop, or the conductor section for a drop limit, in single-phase and three-phase circuits.
Copper resistivity is 1/58 ohm·mm²/m and aluminium is 0.0282, about 20 °C. Reactance, temperature and installation ampacity are not included. Local arithmetic only. This is a quantity or geometry estimate, not a code check and not a substitute for a licensed professional.
- Voltage drop
- 6.62069 V
- Voltage drop
- 2.878561 %
- Resistance
- 0.206897 Ω
Drop = 2 × current × ρ × length / area. ρ is in ohm·mm²/m and area is in mm². Copper uses 1/58 and aluminium 0.0282, about 20 °C. This is a resistive estimate.
How to use Voltage Drop Calculator
Enter voltage, current and length. Find the drop from a section, or the section from a maximum drop percent.
How it works
Estimate resistive voltage drop, or the conductor section for a drop limit, in single-phase and three-phase circuits. Copper resistivity is 1/58 ohm·mm²/m and aluminium is 0.0282, about 20 °C. Reactance, temperature and installation ampacity are not included. Local arithmetic only. This is a quantity or geometry estimate, not a code check and not a substitute for a licensed professional.
Example
16 A over 30 m on a 2.5 mm² copper conductor at 230 V.
Questions about Voltage Drop Calculator
Is Voltage Drop Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Copper resistivity is 1/58 ohm·mm²/m and aluminium is 0.0282, about 20 °C. Reactance, temperature and installation ampacity are not included. Local arithmetic only. This is a quantity or geometry estimate, not a code check and not a substitute for a licensed professional. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.