AC Cable Voltage Drop Calculator
Estimate AC voltage drop and conductor loss using entered resistance/reactance per length, power factor, phase relation and conductor-system assumptions.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Apply the conventional small-drop R/X and power-factor approximation, with the correct single/three-phase multiplier and one-way length.
ΔV=kIL(R×PF ± X√(1−PF²)); k=2 single phase or √3 balanced three phase
Worked example
400 V, 50 A, one-way 100 m and R=0.4 Ω/km at unity PF in balanced three phase give about 3.464102 V drop and 300 W conductor resistance loss.
Assumptions and input details
R and X are supplied by you for the actual operating frequency and temperature; no cable catalogue or regulatory limit is loaded. Leading current uses a negative reactive term and may produce a model voltage rise. Unbalance, neutral current, harmonics, reactance coupling, full phasor load flow, ampacity and code compliance are excluded. A result consuming all source voltage is rejected as outside the approximation.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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