Voltage Drop Calculator

Calculate voltage drop in electrical cables and conductors. Determine if your wire size is adequate and calculate power losses in electrical circuits.

Source Voltage (V)

Load Current (A)

One-way Distance (ft)

Wire Gauge (AWG)

Conductor Material

Temperature (°C)

⚡ Voltage Drop Calculator – Accurate Electrical Wire Sizing & Efficiency Tool

When electricity flows through a wire, some energy is lost as heat. This loss results in a voltage drop, meaning the voltage at the end of the wire is lower than at the source. If the voltage drop is too high, it can cause equipment malfunction, energy waste, and safety issues.

Our Voltage Drop Calculator helps you quickly determine the voltage loss in electrical wires and select the correct wire size for your project — ensuring efficiency, safety, and compliance with electrical standards. Calculate proper wire gauge for your electrical installations.

🧠 What Is Voltage Drop?

Voltage drop is the reduction in voltage that occurs when electrical current flows through a conductor. All wires have resistance, and when current passes through, some voltage is "used up" to overcome this resistance.

The longer the wire and the higher the current, the greater the voltage drop.

A voltage drop that is too large can cause:

Dimming lights
Reduced appliance performance
Overheating of conductors
Tripping of breakers or equipment damage

For residential and commercial electrical systems, the recommended maximum voltage drop is typically 3–5% of the supply voltage.

📝 Voltage Drop Formula

The basic voltage drop formula for single-phase AC or DC circuits is:

𝑉_drop = 𝐼 × 𝑅 × 𝐿

Where:

𝑉_drop = Voltage Drop (Volts)
𝐼 = Current (Amperes)
𝑅 = Resistance per unit length (Ohms per unit)
𝐿 = Length of the conductor (one-way, in meters or feet)

For three-phase circuits, the formula is slightly different:

𝑉_drop(3φ) = √3 × 𝐼 × 𝑅 × 𝐿

⚙️ How the Voltage Drop Calculator Works

Our Voltage Drop Calculator simplifies these calculations by letting you input the required values and instantly get the result. Here's how to use it:

Select your system type – Single-phase or Three-phase.
Enter the wire length (one-way distance).
Enter the current flowing through the wire.
Select the wire gauge / size or provide resistance per unit length.
Enter the supply voltage.
Click "Calculate".

You'll instantly see:

Voltage Drop (in volts)
Voltage Drop Percentage
Voltage at the Load End

This allows you to adjust wire sizes or reduce distance to minimize voltage loss.

🏡 Real-Life Example

Imagine you're installing a single-phase 120V circuit to power a shed 150 feet away. The circuit draws 15A of current, and you're using 12 AWG copper wire, which has a resistance of about 0.001588 ohms per foot.

Calculation:
𝑉_drop = 15 × 0.001588 × 150 ≈ 3.57 V

Voltage drop percentage:
(3.57 / 120) × 100 ≈ 2.98%

✅ Result: This is within the recommended 3% limit, so the wire size is acceptable. If the voltage drop were higher, you could use a larger wire gauge to reduce resistance.

💡 Why Use the Voltage Drop Calculator?

Manual calculations can be tricky, especially when working with different wire sizes, lengths, and current values. Our calculator offers:

✅ Instant calculations
– no formulas needed

✅ Accurate results
– for both single-phase and three-phase circuits

✅ Support for different wire sizes
– copper, aluminum, etc.

✅ Voltage drop percentage
– check against standards

Whether you're an electrician, engineer, or DIY enthusiast, this tool makes your work easier and safer.

❓ Frequently Asked Questions (FAQs)

1. What is an acceptable voltage drop?

A: Most electrical codes recommend keeping voltage drop below 3% for branch circuits and below 5% for feeders to ensure proper performance.

2. Does wire material affect voltage drop?

A: Yes. Copper has lower resistance than aluminum, so copper wires experience less voltage drop for the same size and length.

3. Can voltage drop damage equipment?

A: Yes. Excessive voltage drop can cause motors to run hot, lights to dim, or sensitive electronics to malfunction.

4. Can this calculator be used for DC circuits?

A: Yes. For DC systems (such as solar installations), the single-phase formula applies. Just make sure to input correct values for wire length, current, and resistance.

5. How can I reduce voltage drop in my circuit?

Use thicker (lower gauge) wire
Shorten the cable length if possible
Reduce the current draw
Increase the supply voltage (where safe and applicable)

📝 Final Thoughts

Voltage drop is often overlooked but plays a critical role in electrical efficiency and safety. Calculating it manually can be complex, but with our Voltage Drop Calculator, you can get fast, accurate, and reliable results.

👉 Try it now and design your circuits the right way: Use the Voltage Drop Calculator on voltagecalculator.online