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Can I use this result for planning?

Yes, but treat it as a starting point and compare it with your real situation before making a final decision.

What should I do after using the Voltage Drop Calculator?

Review the explanation, test one alternative scenario, and use the result as a starting point before making your final decision.

Why does this page include guidance below the tool?

The guidance helps you understand the result, avoid common mistakes, and choose a practical next step instead of only seeing a number.

Home / Engineering Intelligence / Electrical Engineering Intelligence / Voltage Drop Calculator

Voltage Drop Calculator

Calculate Electrical Engineering Intelligence

Estimate voltage drop across a cable from current, length, resistance, and phase type.

Voltage drop calculator

Get the answer first

Estimate voltage drop before verifying conductor size, protection, and code requirements.

EnterCurrent amps, One-way length m, Resistance ohms/km
CalculateExample: 20 A, 30 m one-way run, 5.8 ohms/km, and 120 V estimates about 6.96 V drop.
DecideCompare cable size, circuit load, and Ohm law calculators.

Start calculator

Example

Example: 20 A, 30 m one-way run, 5.8 ohms/km, and 120 V estimates about 6.96 V drop.

Avoid this mistake

Electrical work can cause shock, fire, arc flash, and equipment damage. Verify conductor material, temperature, conduit fill, derating, protection, grounding, and local code.

Related path

Pick the right calculator path

Use these guided hubs when the calculator result points to a bigger decision or a related search intent.

Electrical Calculator Hub Use Ohm law, wattage, voltage drop, load, wire, power, and electrical planning calculators with safety-aware guidance.

Electrical engineering safety note

Electrical engineering calculators on ToolsBing are preliminary educational and planning tools only. Electrical work can create shock, fire, arc-flash, equipment damage, and code-compliance risks. Verify all calculations with licensed electricians, qualified engineers, manufacturer data, local electrical codes, protective-device requirements, and safety standards before installation or operation.

Enter electrical engineering inputs

Current AOne-way Length mConductor Resistance Ω/kmSystem Voltage V

Estimated result

ResultWaiting for input

V drop / %

ConfidencePlanning estimate

Use for education, early planning, and comparison only.

Next stepCheck code and protection

Verify conductor ratings, breaker/fuse sizing, derating, grounding, environment, and local code requirements.

Formula and assumptions

Voltage drop ≈ current × conductor resistance × circuit length

This calculator uses simplified electrical assumptions. Real systems may require derating, conductor temperature ratings, insulation type, installation method, short-circuit protection, coordination studies, power quality review, and licensed professional verification.

Related electrical calculators

Next useful step

Use the result without guessing

Before you act, run one real scenario and one conservative scenario.

Refine inputsReplace the example with your real values. Check methodSee what the calculator includes and leaves out.

Watch forElectrical work can cause shock, fire, arc flash, and equipment damage. Verify conductor material, temperature, conduit fill, derating, protection.

Known input

20 A load, 30 m one-way run, conductor resistance 5.8 ohms/km, 120 V system.

Expected result

Displayed voltage-drop estimate should be about 6.96 V.

Method check

Voltage drop = current x conductor resistance x round-trip length. Allow +/- 0.2 V because conductor temperature and material assumptions vary.

Related path

Continue with a focused hub

Use these guided hubs when the calculator result points to a bigger decision or a related search intent.

Electrical Calculator Hub Use Ohm law, wattage, voltage drop, load, wire, power, and electrical planning calculators with safety-aware guidance.

Check before using this result

Verify the inputs, units, assumptions, and any local rules that apply. For financial, health, engineering, or construction decisions, confirm the result with a qualified professional or an authoritative source.