Wire Power Loss Calculator

Calculate loop resistance for the complete source-load-return path, then use Ploss = I²Rloop. The same loss also equals I × Vdrop.

I²R loss is P = I²R, where I is conductor current and R is the resistance carrying that current.

Resistive power loss rises with the square of current. Doubling current through the same loop resistance produces four times the heat-producing loss.

For a two-conductor DC cable, compute Rsingle = ρL/A, Rloop = 2Rsingle, and Ploss = I²Rloop.

Use R = ρL/A for one conductor. For a source-and-return DC cable pair, use Rloop = 2ρL/A.

Current flows through the outgoing conductor and returns through another conductor, so both conductors dissipate power.

Single-conductor loss is I²Rsingle. Total loop wire loss is the combined loss in the outgoing and return conductors.

Wire power loss scales with current squared. A small current increase can cause a much larger loss increase.

At fixed current, material, and area, doubling one-way length doubles loop resistance and doubles total wire loss.

A larger conductor area reduces resistance and lowers I²R loss for the same length and current.

Lower AWG numbers generally mean larger conductors, lower resistance, less voltage drop, and less I²R loss.

Copper has lower resistivity than aluminum, so the same area and length usually dissipate less power in copper.

If current is known and nonzero, Vdrop = Ploss / I. The calculator also computes Vdrop directly from I × Rloop.

Because Vdrop = IR. Substituting IR for voltage in P = IV gives P = I²R.

Energy loss is Eloss = Ploss × time. The calculator reports joules, watt-hours, and kilowatt-hours.

Watts measure power at an instant. Watt-hours measure energy accumulated over time.

One watt-hour equals 3600 joules. One kilowatt-hour equals 3.6 million joules.

Wire delivery efficiency is the load power after conductor drop divided by source electrical power in the simple DC conductor model.

No. It only estimates conductor delivery efficiency and excludes source, converter, switch, connector, and load efficiency.

Yes. Resistance changes with conductor temperature, so real I²R loss can differ from the reference-resistivity estimate.

No. It calculates electrical heating power, not conductor operating temperature or temperature rise.

No. It does not verify safe current, ampacity tables, insulation rating, bundling, or installation method.

Only as a simple low-frequency resistive estimate. Complete AC conductor loss may require RMS current, AC resistance, skin effect, proximity effect, and phase conditions.

Yes. Connector and terminal resistance can add I²R loss, but this calculator does not include it unless you include it in a known loop resistance input.

The raw conductor loss is calculated, but load power and delivery efficiency are marked not physically meaningful under the simple source-and-wire model.