Voltage Drop Calculator
Voltage drop = 2 × Length × Resistance × Current (for single-phase)R≈1.588Ω/1000ft; drop=2×0.1×1.588×10≈3.18V (2.65%)
Free online tool
Voltage Drop Calculator
Enter the supply voltage, current, wire length and wire gauge.
Instant calculation
Voltage Drop Calculator
Enter the supply voltage, current, wire length and wire gauge.
Your result
Calculation
Your numbers stay in this browser. Nothing is uploaded or saved.
Three clear steps
How to use this calculator
- 01
Enter voltage
Type the supply voltage.
- 02
Enter current
Type the current in amps.
- 03
Enter distance and wire size
Provide the one-way distance and wire gauge.
The formula
How this calculation works
Voltage drop increases with distance and current. Keep under 3-5% for most applications.
Check the method
Worked examples
Each example follows the same formula used by the calculator.
120V, 10A, 100 ft, 12 AWG — voltage drop?
R≈1.588Ω/1000ft; drop=2×0.1×1.588×10≈3.18V (2.65%)≈ 3.18V drop (2.65%)Common questions
Questions about this calculation
What is the Voltage Drop Calculator?
The Voltage Drop Calculator helps you calculate voltage drop in an electrical circuit. Enter your values and select Calculate to get an instant result.
How is the result calculated?
Voltage drop increases with distance and current. Keep under 3-5% for most applications.
Can you show an example?
Example: 120V, 10A, 100 ft, 12 AWG — voltage drop? — ≈ 3.18V drop (2.65%).
Is my data saved when I use the Voltage Drop Calculator?
No. All calculations run locally in your browser. Your inputs and results are never uploaded, stored or shared with anyone.
Is the Voltage Drop Calculator free to use?
Yes. The Voltage Drop Calculator is completely free. No account, sign-up or payment is required. It works on mobile, tablet and desktop.
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