Voltage Drop Calculator
Estimate DC two-conductor voltage drop from entered wire resistance.
Formula and method
Estimate DC two-conductor voltage drop from entered wire resistance. The result is calculated with the relationship below and rounded only for display.
Voltage drop = current × resistance per length × round-trip lengthWorked example
10 A through 40 m round trip at 0.005 Ω/m drops 2 V.
How to use this calculator
- Enter measurements or values in the labelled fields.
- Keep all inputs in the units shown beside each label.
- Select the relevant method or direction where offered.
- Choose Calculate and review the result plus supporting details.
Assumptions and limitations
This is an educational planning tool. It does not automatically account for local building practice, taxes, fees, rounding rules, measurement uncertainty, safety margins, or professional standards unless you enter them. Check important results independently.
Frequently asked questions
The arithmetic follows the formula shown on this page. Real-world accuracy still depends on the measurements, rates, assumptions, and rounding you enter.
No. The calculation runs in your browser and this page does not require an account or send the entered values to a calculation server.
Use it as a planning or checking estimate. For high-cost, safety-critical, academic, tax, or regulated decisions, confirm the result with a qualified professional or authoritative science & engineering source.
References and further reading
These sources explain relevant standards, methods, or official guidance. References do not imply endorsement.