Engineering
Voltage Drop Calculator
Estimate DC two-wire voltage drop from supply voltage, current, one-way length, conductor area, and material resistivity. Review delivered voltage, power loss, conductor-size scenarios, and export a professional PDF engineering estimate.
Loop resistance-
Voltage drop-
Voltage drop percentage-
Delivered voltage-
Cable power loss-
Conductor sizing
Voltage drop across standard conductor areas
Voltage drop percentageTwo-way DC circuit using the entered length, current and resistivity
| Area | Loop resistance | Voltage drop | Drop % | Delivered voltage | Power loss |
|---|
Cable run
Supply voltage to delivered voltage path
Cable resistance, drop, delivered voltage, and watt loss stay in one run diagram.
Supply voltage to delivered voltage path
Supply0 V
0 V drop
Delivered0 V
Drop percent0%
Cable loss0 W
Conductor area0
How to use Voltage Drop Calculator
- Enter supply voltage, current, one-way cable length, conductor area, and conductor resistivity.
- Check delivered voltage and percentage drop before judging only the watt loss.
- Use conductor-size scenarios to see whether increasing area materially improves delivered voltage.
Calculator guide
Understanding Voltage Drop Calculator
Voltage drop occurs because a conductor has resistance. A two-wire DC circuit includes both the outgoing and return conductor, so length, current, material, and cross-sectional area all affect delivered voltage and power loss.
Calculation method
How the calculation works
DC two-wire voltage drop = 2 x one-way length x current x conductor resistance per unit length. Calculate loop resistance as twice the one-way length multiplied by material resistivity and divided by conductor area. Multiply by current for voltage drop and by current squared for conductor loss.
Voltage drop method
Before using the result
Worked situations
Practical examples
- Use Voltage Drop Calculator for a quick everyday estimate.
- Change any input to compare another scenario.
Better inputs
Useful tips
- Use the actual conductor material and cross-sectional area.
- Allow for higher resistance at elevated operating temperature.
- Check applicable electrical codes, protection, ampacity, and terminal ratings separately.
Before relying on the result
Limitations and common mistakes
- The model is a simplified two-wire DC estimate.
- AC reactance, power factor, temperature rise, connections, and harmonics are excluded.
- It is not a conductor-sizing approval or code-compliance determination.
Reference
Key terms
- Resistivity
- Material property relating resistance to length and area.
- Loop length
- Combined outgoing and return conductor distance.
- Voltage drop
- Potential lost across conductor resistance.
- Power loss
- Electrical power converted to heat in the conductor.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Why is one-way length doubled?
Current travels through both outgoing and return conductors in the modeled circuit.
Why does larger cable reduce drop?
Resistance is inversely proportional to conductor cross-sectional area.
Does this model AC circuits?
No. It omits reactance and power factor.
What voltage-drop percentage is acceptable?
Limits depend on system purpose, equipment, local code, and design practice; consult applicable standards.