Voltage Drop Calculator
Calculate voltage drop in electrical wiring from wire length, current, cross-section and material.
For 3-phase systems, multiply the voltage drop by 0.866. Per Indian wiring standard IS 732, voltage drop should be kept under 3% for lighting circuits and under 5% for other loads.
What is Voltage Drop Calculator?
The Voltage Drop Calculator computes the voltage lost across a wire run based on length, current, conductor cross-section, and material type.
Excessive voltage drop causes dim lights, overheating, and inefficient operation of electrical equipment. Indian wiring standard IS 732 recommends keeping voltage drop under 3% for lighting and 5% for other loads.
How does the Voltage Drop Calculator work?
The formula uses resistivity (rho) of the conductor material: 0.0172 ohm-mm²/m for copper and 0.0282 ohm-mm²/m for aluminum.
Wire length is doubled because current must travel to the load and return. The cross-sectional area (A) in mm² determines how easily current flows through the wire.
How to use the Voltage Drop Calculator?
- Enter the one-way wire length in meters from the source to the load.
- Enter the current in amperes that the circuit will carry.
- Select the wire cross-section in mm² and the conductor material from the dropdowns.
- Choose the system voltage and review the wire resistance, voltage drop, and percentage on the right.
Example
Try the calculator with your own numbers
- Enter your values in the input fields above.
- Adjust the values to match your situation.
- The result updates instantly as you change the inputs.
Benefits of using the Voltage Drop Calculator
- Quickly verifies whether a proposed wire size meets voltage drop limits for the application.
- Supports both copper and aluminum conductors with accurate resistivity values.
- References Indian standard IS 732 thresholds for lighting and power circuits.
Who should use the Voltage Drop Calculator?
- Students and professionals who need fast, accurate results.
- Anyone who wants to verify a manual calculation.
- People who prefer a quick answer over working it out by hand.
Tips for getting the most out of the Voltage Drop Calculator
- Double-check the values you enter before relying on the result.
- Use the calculator to verify manual calculations or estimates.
- Bookmark the page if you use it regularly.
Frequently Asked Questions
Why is wire length doubled in the calculation?
Current flows from the source to the load and back via the return conductor, so the total conductor length is twice the one-way distance.
What voltage drop percentage is acceptable?
Per IS 732, keep voltage drop below 3% for lighting circuits and below 5% for other loads. Exceeding these limits causes equipment malfunction and energy waste.
How do I reduce voltage drop?
Use a larger wire cross-section, reduce the wire length, lower the current load, or choose a conductor material with lower resistivity (copper over aluminum).
This calculator gives you fast, reliable answers whenever you need them. Try it now and keep it handy for future calculations.
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