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DC and AC Voltage Drop Calculator

Calculate DC path drop or approximate single-phase and balanced three-phase AC drop using actual conductor data, circuit current and a chosen limit.

Use this result well

Inputs that matter
Circuit and conductor specification, Source DC voltage (V), Chosen comparison limit (%), Sequential path segments, and 8 more
Output to expect
DC path voltage drop, AC steady-load voltage drop
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

DC path voltage drop

Total resistance-only voltage drop along a documented DC path to one endpoint. Enter each sequential segment's actual current and the resistance of its outgoing and return conductors at the intended temperature. A segment current includes the downstream loads it supplies; the tool does not solve a branching network or select wire size.

Segment drop = amperes × one-way meters × (outgoing + return ohms/km) ÷ 1000; endpoint drop is the sum of segment drops.

AC steady-load voltage drop

Estimate longitudinal voltage drop for a sinusoidal single-phase two-wire circuit or a balanced three-phase circuit at unity or lagging power factor. Use documented AC resistance and inductive reactance at the actual frequency, temperature and conductor arrangement. The entered current is the current in each line; no wire table or default material is assumed.

Approximate drop = k × current × one-way meters ÷ 1000 × (R × PF + X × sqrt(1 − PF²)); k = 2 for single phase or sqrt(3) for balanced three phase.

Updated: September 2026

Example Scenarios

The built-in example is an arithmetic illustration. Replace it with your own verified measurements or planning assumptions.

→ 0.66 V path drop

The built-in example is an arithmetic illustration. Replace it with your own verified measurements or planning assumptions.

→ 1.4976 V approximate drop

FAQ

No. This checks voltage-drop arithmetic against your chosen limit. Ampacity, protection, equipment requirements and installation rules need separate review. Unknown wire resistance is never replaced by a default AWG.

Use the actual source documents, units and operating conditions shown in the selected mode. Replace illustrative examples with your records, enter explicit zeros only where valid and retain unresolved assumptions.

Choose Save planning case for local history. Copy MD retains current inputs, notes and interpretation; Download CSV exports the result breakdown. Export a separate copy before changing devices or clearing browser storage.

About DC and AC Voltage Drop Calculator

Total resistance-only voltage drop along a documented DC path to one endpoint. Enter each sequential segment's actual current and the resistance of its outgoing and return conductors at the intended temperature. A segment current includes the downstream loads it supplies; the tool does not solve a branching network or select wire size. Estimate longitudinal voltage drop for a sinusoidal single-phase two-wire circuit or a balanced three-phase circuit at unity or lagging power factor. Use documented AC resistance and inductive reactance at the actual frequency, temperature and conductor arrangement. The entered current is the current in each line; no wire table or default material is assumed.