Voltage Drop Calculator

Calculate the voltage drop across components in electrical circuits. A must-have tool for electrical engineers and technicians.

Wire type:
Wire diameter size:
Wire/cable length (one way):
Current type:
Voltage in volts:
Current in amps:
Voltage drop in volts:
Percentage of voltage drop:
Wire resistance:

Voltage drop refers to the reduction in electrical potential (voltage) that occurs as current flows through a conductor, typically a wire or circuit. When electricity travels through a wire, it encounters resistance from the material of the wire itself. This resistance causes some of the electrical energy to be converted into heat, resulting in a decrease in voltage along the length of the wire.

Think of voltage drop like water flowing through a pipe. If the pipe is narrow or has obstacles, the water experiences resistance, causing a drop in pressure as it travels through the pipe. Similarly, in an electrical circuit, as current flows through a wire, the wire's resistance causes a drop in voltage.

Voltage drop is influenced by several factors, including the material and size of the wire, the length of the wire, the amount of current flowing through the circuit, and environmental conditions such as temperature. It is essential to consider voltage drop in electrical systems to ensure that devices receive the required voltage for proper operation and to prevent overheating of wires, which can lead to safety hazards like fires.

Voltage Drop equation and formula

The equation used to calculate voltage drop in a circuit is Ohm's Law, which states:

V = I × R


To calculate voltage drop, rearrange the equation to solve for 

V = I × R

For example, if you have a circuit with a current of 10 amperes flowing through a wire with a resistance of 2 ohms, the voltage drop can be calculated as follows:

V = 10A × 2Ω

V = 20V

So, the voltage drop in this circuit would be 20 volts.

Additionally, for practical calculations involving wire length and material, the following formula is commonly used to calculate voltage drop:

VD = (2 × R × L × I) / (C×A)


Benefits of Using a Voltage Drop Calculator

Accuracy: Calculators provide precise voltage drop values, eliminating guesswork.

Time-saving: Automating calculations saves time compared to manual methods.

Compliance: Ensures adherence to safety standards and regulations.

Optimization: Helps optimize wire size and circuit design for efficiency.

Frequently Asked Questions

The acceptable voltage drop for residential wiring typically depends on local electrical codes and standards.

However, a commonly accepted guideline is to keep voltage drop below 3% for branch circuits and below 5% for feeder circuits to ensure efficient performance of electrical appliances and devices.

Yes, advanced voltage drop calculators may incorporate temperature factors into their calculations. Temperature affects the resistance of the wire, which in turn influences voltage drop.

Calculators that consider temperature variations provide more accurate results, especially in environments where temperature fluctuations are significant.

Yes, voltage drop calculations are crucial for low-voltage systems as well. While the impact of voltage drop may be less pronounced in low-voltage circuits compared to higher-voltage circuits, it can still affect the performance of devices and equipment.

Therefore, accurate voltage drop calculations are essential to ensure proper operation and prevent issues such as dimming lights or reduced power delivery.

In industrial settings, voltage drop calculations should be performed whenever designing or modifying electrical systems, especially for long-distance power distribution or critical applications.

Additionally, periodic checks may be necessary during maintenance or system upgrades to ensure continued reliability and compliance with safety standards.