Voltage Drop Calculator
Calculate voltage drop in electrical wire runs for any circuit length and load.
Voltage Drop Calculator
Calculate voltage drop in electrical wire runs for any circuit length and load.
Engineering Calculation
ℹ️ Used for basic engineering ratio and product calculations
Disclaimer
Results provided by this calculator are for informational and educational purposes only. They are based on the values you enter and standard formulas, and should not be considered financial, medical, legal, or professional advice. Always consult a qualified professional before making important decisions based on these results. Roughtools makes no warranties regarding the accuracy or completeness of these calculations for your specific situation.
Frequently Asked Questions
Pro Tips
Always verify critical calculations with a second method or source — for important decisions, this tool provides a starting point, not a final answer.
Input accuracy determines output accuracy. Use precise values rather than rough estimates for the most useful results.
Run the calculation multiple times with slightly different inputs to understand the sensitivity of the result to your assumptions.
For professional, financial, medical, or legal decisions, always confirm results with a qualified professional before acting.
When to Use This Calculator
Use the Voltage Drop Calculator for fast, accurate calculations without installing any software.
Understand the formula and see how changing inputs affects the result for educational purposes.
Get a quick estimate before performing more detailed analysis or consulting a professional.
Accessible from any device — no app to install, no account required, works offline after loading.
Run multiple scenarios quickly by changing one input at a time to understand sensitivities.
About the Voltage Drop Calculator
This voltage drop calculator computes the voltage loss across any electrical conductor using the standard formula V = (2 × L × R × I) / 1000 for single-phase circuits, where L is one-way run length, R is resistance per 1000 ft (from NEC wire tables), and I is current in amps. Enter wire gauge (AWG), conductor material (copper or aluminum), run length, and load current to see voltage drop, percentage drop, and whether it meets NEC guidelines (≤3% for branch circuits, ≤5% total). Built for electricians, contractors, and engineers sizing wire runs.
How to Use the Voltage Drop Calculator
- 1
Select the circuit type: single-phase or three-phase.
- 2
Enter the one-way wire run length in feet.
- 3
Select the wire gauge (AWG) and conductor material (copper or aluminum).
- 4
Enter the load current in amps.
- 5
See voltage drop in volts, percentage drop, and NEC compliance status.
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