Voltage Drop Calculator
An essential tool for electrical calculations and proper wire sizing.
What Is This Calculator?
This tool is a comprehensive voltage drop calculator designed for electricians, engineers, and DIY enthusiasts. It simplifies the complex task of calculating voltage drop to ensure safety and efficiency in any electrical circuit. Whether you need a dc voltage drop calculator for a solar project or an AC cable voltage drop calculator for a home wiring run, this tool provides the accuracy of a professional utility like the Southwire voltage drop calculator with a simple, easy-to-use interface. Our goal is to make any voltage drop calculation fast and understandable, eliminating the need to manually consult a voltage drop calculation table or perform complex math. Think of this as the ultimate voltage drop in wire calculator for your projects.
How to Calculate Voltage Drop
- Select System ParametersChoose your system type, wire material, and the initial source voltage of your circuit.
- Enter Load & Wire DetailsInput the current (Amps) drawn by your load. Then, use the dropdown as a voltage drop calculator wire size selector to choose the correct gauge for your cable.
- Provide Circuit LengthEnter the one-way distance in feet from your power source to the load. The calculator automatically doubles this for the total circuit length in its voltage drop calculations.
- Calculate and AnalyzeClick “Calculate” to see the results. The key value is the voltage drop percentage, which will be color-coded for quick NEC compliance checks.
Frequently Asked Questions
The primary voltage drop calculation formula is VD = (Multiplier) x K x I x L / CMA. For DC or AC Single-Phase, the Multiplier is 2. For AC Three-Phase, it’s √3 (~1.732). ‘K’ is the resistivity constant, ‘I’ is current, ‘L’ is one-way length, and ‘CMA’ is the Circular Mil Area of the wire. This tool automates this complex calculation for voltage drop of cable.
Many users ask this. A resistor voltage drop calculator solves for Ohm’s Law (V=IR) across a specific component. This is a wire voltage drop calculator that solves for voltage loss across the entire length of a cable. While you could manually calculate voltage drop across a resistor that represents the wire, this tool does it automatically and is essential for correct wire sizing.
The NEC (National Electrical Code) generally recommends a maximum voltage drop of 3% for a branch circuit. Our nec voltage drop calculator uses this 3% rule to color-code the results green (pass) or red (fail). For a sensitive low voltage drop calculator scenario, like a 12v voltage drop calculator for outdoor lighting, keeping the drop below 5% for the entire circuit is critical.
Every wire has a small amount of resistance per foot. Over a short distance, this is negligible. But over a long run, the total resistance adds up, creating a larger voltage drop. That’s why a wire length voltage drop calculator is so important for long-distance applications like powering an outbuilding or for solar panel arrays, where a specialized solar voltage drop calculator would be used.
This tool is a fully functional 3 phase voltage drop calculator. Three-phase power is more efficient for long-distance power transmission, which is why the formula uses a smaller multiplier (√3 instead of 2). You can simply select “AC Three-Phase” from the System Type dropdown to perform the correct ac voltage drop calculation.
While this tool functions as an excellent voltage drop wire size calculator for *verifying* your choice, it doesn’t directly recommend a size. The standard method is to input your details with a chosen wire size. If the voltage drop percentage is too high (i.e., the result is red), you should select the next-largest wire size (a smaller AWG number) and re-calculate until the result is acceptable.
This calculator is designed to find the voltage drop on a single run of cable. For a simple series circuit, you would perform a voltage drop calculation for each segment and add them together. To calculate voltage drop in a parallel circuit is more complex, as the current divides among the branches. You would need to calculate the drop for each parallel branch separately based on the current flowing through that specific branch.
