DC Voltage Drop Calculator

for CCTV Security Camera Power Systems

Maximum Voltage Drop

Industry Standard is maximum of 10% drop or a minimum voltage or 10.2 for a 12 volt CCTV or HD security camera

Amps (A) from Milli-amps (mA)

Some security camera specification sheets use mA instead of A – simple divide mA by 1000

800mA = 0.8A

Common Wire Gauges

RG59 Siamese (18/2) – 18AWG

Cat5e – 24AWG

Cat6 – 23AWG


Using Ohm’s Law Method

Voltage Drop = Load * Resistance

Resistance based on AWG resistance tables multiplied by complete circuit distance

Input Voltage

CCTV Power Supply Voltage, Typically 12.5 to 13.2 volts for 12 volt systems and 24.5 to 25.5 volts for 24 volt systems.


Pure copper or CCA (Copper Clad Aluminum) NOTE: CCA adds significant resistance since the wire core is mostly aluminum.

Wire Gauge

Most professional CCTV cable is 18AWG.  Select the exact gauge for proper voltage  drop calculation.

Current Draw

Use max current draw (including IRs) in Amps from camera specifications


Measured cable distance from Power Supply to Camera.