Engineering / Browser calculator

Voltage Drop Calculator

Voltage Drop Calculator works from the inputs you provide and returns resistance (ω), voltage drop (v), voltage drop (%), load voltage (v). Use the calculation panel to explore a scenario, then check the formula and limitations before applying the result.

Your inputs

Minimum: 0
Minimum: 0
Minimum: 1e-06
Minimum: 1e-06
Minimum: 1e-06

Your results

Enter your values and calculate to see the result.

Estimates depend on the stated method and entered quantities. Check applicable standards before using a result for a real-world design or safety decision.

Formula and calculation method

Loop resistance = 2 × length × resistivity / area. Voltage drop = current × loop resistance.

DC two-wire or resistive single-phase approximation. Excludes AC reactance, temperature changes and code compliance.

How to use voltage drop calculator

  1. Set Current (A). The example below uses 10.
  2. Set One-way cable length (m). The example below uses 20.
  3. Set Cross-section (mm²). The example below uses 2.5.
  4. Set Resistivity (Ω·mm²/m). The example below uses 0.0175.
  5. Set Supply voltage (V). The example below uses 230.
  6. Select Calculate to update the result. Reset restores the illustrated inputs. Copy, print or download your own result if you need a record.

Worked example

Example inputs
Current (A)
10
One-way cable length (m)
20
Cross-section (mm²)
2.5
Resistivity (Ω·mm²/m)
0.0175
Supply voltage (V)
230
Resistance (Ω)
0.28
Voltage drop (V)
2.8
Voltage drop (%)
1.2173913
Load voltage (V)
227.2

Factors affecting your result

DC two-wire or resistive single-phase approximation. Excludes AC reactance, temperature changes and code compliance.

Changing current (a) changes the scenario being evaluated. Adjust one input at a time when comparing results, keep a copy of the assumptions, and compare values using the same unit and period. A precise arithmetic result does not make an uncertain assumption precise.

Frequently asked questions

How does the voltage drop calculator work?

Loop resistance = 2 × length × resistivity / area. Voltage drop = current × loop resistance.

What inputs does Voltage Drop Calculator need?

Enter current (a), one-way cable length (m), cross-section (mm²), resistivity (ω·mm²/m), supply voltage (v). Choose values that correspond to the same situation and measurement convention.

How should I interpret the voltage drop calculator result?

DC two-wire or resistive single-phase approximation. Excludes AC reactance, temperature changes and code compliance.

Are my voltage drop calculator inputs uploaded?

No. The calculation runs in this browser. Favorites, recent tool names, theme and formatting preferences may be saved locally, but calculation inputs are not sent to a calculation server or stored by this website. Shared links do not include entered values.

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