Cable Voltage Drop and Loss Calculator
Enter the applicable resistance yourself. Use Vdrop = I × R and Ploss = I² × R; the existing length mode also shows source-voltage percentage and voltage at load.
A QUICK WALKTHROUGH
How to use this tool
- Choose direct total resistance or the existing length-based mode.
- Enter current and resistance, or positive source voltage, current, length and resistance per km or 1,000 ft with 1 or 2 conductors.
- Optionally enter 1–20 current multipliers; calculate, review all rows, then copy or download the report.
Resistance is your input
Direct mode uses total applicable loop resistance. Length mode converts one-way length and resistance per selected distance unit, multiplied by 1 or 2 conductors.
Current scenarios
Each multiplier q defines Iq = I × q, Vq = Iq × R and Pq = Iq² × R. Zero current or zero direct resistance yields zero drop and loss.
Fixed local report
All inputs and computed rows stay in the browser. A successful calculation creates a report with raw and parsed values, units, model and full numerical precision; input edits clear it.
GOOD TO KNOW
Common questions
What does power loss mean?
It is power dissipated in the entered resistance, calculated as I²R in watts; it is not energy in watt-hours.
What happens to the previous length mode?
It retains positive inputs, meter/feet and Ω/km or Ω/1,000 ft conversion, 1 or 2 conductors, source voltage, drop percentage and load voltage. A drop exceeding source voltage is rejected.
Does this select or rate a cable?
User-defined applicable total loop resistance; an ohmic resistor model. No ampacity, temperature, rating, code-limit or cable-design evaluation.