Ohm's law calculator and coax cable loss estimator for ham station planning. Works offline. Works offline after your first visit.

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Ohm's Law & Coax Loss

Enter any two of V, I, R, P — solve the rest. Estimate feedline loss by cable type and length.

Ohm's law

Fill in any two fields; leave others blank.

Coax loss estimate

Common questions

Why do hams need Ohm's law?

Voltage, current, and resistance for power systems, antenna matching, and license exam questions.