Physics & Electrical calculator

Voltage Drop Calculator

Enter one-way route length, current, conductor area and system voltage for a preliminary voltage-drop estimate.

Calculated privately on your device
No account. Formula and assumptions are shown below.

Calculator inputs

Voltage drop details

Formula & disclaimer

Single-phase Drop = 2 × Length × Current × Resistivity ÷ Area; Three-phase Drop = √3 × Length × Current × Resistivity ÷ Area

View assumptions

Formula reviewCalcs at Hand Editorial TeamVerified 31 August 2026 · automated checks included

Three useful checks, kept deliberately short.

What this result includes

The simplified resistive estimate is about 5.25 V, or 2.28%.

A practical example

30 m copper run, 20 A, 4 mm² and 230 V single-phase: Use copper resistivity · Include outgoing and return conductors · Divide by conductor area.

Common input mistake

Operating temperature, grouping, harmonics and installation method can change the final design.

Single-phase Drop = 2 × Length × Current × Resistivity ÷ Area; Three-phase Drop = √3 × Length × Current × Resistivity ÷ Area

The formula uses conductor resistivity at approximately 20°C and omits reactance.

Keep in mind: This is a preliminary resistive estimate, not an electrical design or compliance check.

Produced byCalcs at Hand Editorial Team

Last formula check31 August 2026

Review methodKnown examples + boundary cases