Voltage Drop Calculator

This calculator will estimate the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current. Please note this calculator assumes that the circuit is operating in a normal condition - room temperature with a normal frequency.

The actual voltage drop of your circuit may vary based on the condition of the wire, the conduit being used, the temperature, the connector, the frequency, etc. It is recommended that the voltage drop should be less than 5% under a fully loaded circuit condition. 

What causes voltage drop?

The cause of voltage drop is that conductors have some resistance to the flow of electrons when an electrical current passes through it. Voltage drop refers to the loss of electrical potential (voltage) when current flows through a conductor. This relationship can be explained by using Ohm's Law, in which voltage (V) is equal to the current (I) and resistance (R), expressed as V = I * R. Ohm's law is used to calculate the voltage drop in relation to the current and resistance of a conductor. Voltage drop can occur in various elements of an electrical circuit. Excessive voltage drop can cause a power and performance loss within the circuit. To minimize voltage drop, a common strategy is using larger gauge wires or cables with a lower resistance. Other strategies to minimize voltage drop are reducing the length of the conductor, or using more conductive materials.

Required Data Entry
Select Material
Select Size
Select Voltage and Phase
Enter Cable Length Feet
Enter Load Amps
Estimated Volt Drop
Volt Drop %