Wire Size/Weight Calculator

Use this calculator when you want to choose which gauge wire to use for your small application (like radio controlled aircraft). This calculator will estimate the power lost in the wire and the weight of the wire (copper weight only). If you have any questions about cable or harness testing call us toll-free 1-800-441-9910.


Wire gauge
Step 1: Define the Load
The Load
Diagram of calc model Peak load current (I)(Amps)
Max source voltage (Vs)(volts)

Step 2: Compare Different Wires
Wire Choice 1

Length Units

Wire length from source to load
___ ohms
  Point B:  Length Gauge ___ ohms

Contact resistance from fixture to DUT:
  At Point A: ohms ___ ohms
  At Point B: ohms

___ ohms
Your Device Under Test 
Wire in DUT:
  Length Gauge

___ ohms
Wire Resistance Results 

Expected resistance of:
   A 2-wire measurement:___ ohms
   A 4-wire measurement (points combine at A and B):___ ohms
   4-wire measurement (points combine on DUT):  

___ ohms
Step 3: Factor in the Variations
Wire Resistance %
Wire Length %
Max Temperature ° ___%
°F or °C

Accuracy of Tester
  Percent of reading %
  Fixed error ohms

Recommended Thresholds 
Highest Expected Resistance for 2-wire:___ ohms
Highest Expected Resistance for 4-wire (points combine at A and B):___ ohms
Highest Expected Resistance for true 4-wire (points combine on DUT):___ ohms