Kelvin (4-Wire) Resistance Estimator
Enter the known values and run the calculation.
Overview
Support low-resistance measurement planning where lead resistance and contact effects matter.
This estimator compares a 2-wire resistance reading to the ideal 4-wire result when lead resistance is part of the measurement path.
It is aimed at low-resistance work where fixture leads, clips, pogo contacts, and cable losses can add enough error to matter.
The math and how it's used
For a 2-wire measurement, the measured resistance is the DUT plus the series lead resistance in the current path.
For a 4-wire Kelvin measurement, the force and sense paths are separated, so the voltage drop in the force leads does not materially bias the measured DUT value.
The point of this tool is to show when a perfectly ordinary lead or clip resistance is large enough to corrupt a low-ohm measurement and when a four-wire setup stops being optional.
That makes it useful for shunts, contacts, winding resistance, and harness work where the fixture can be a meaningful part of the reading.
When to switch to Kelvin
Use Kelvin methods when the expected lead resistance is not negligible compared to the DUT, or when pass/fail limits are tight enough that a few milliohms matter.
This comes up with shunts, contact resistance checks, winding resistance, cable harness verification, and power-path debugging.