50 Ω RF Calculator
Calculate RF power, RMS/peak voltage, current and resistance for a resistive load.
For a resistive load. Enter any two compatible quantities; power and resistance are used by default. Peak voltage/current are also shown for sine-wave RF.
Keep the 50-ohm reference clear
The 50-ohm relationship is a compact way to move between RF power, RMS voltage and RMS current when the impedance is known. It is especially useful for checking instrument readings and estimating stress on connectors and components.
The calculation assumes a resistive 50-ohm load. A reactive or mismatched load can have the same average power while showing different voltage and current distributions at different points in the system.
Use RMS values when comparing to average power. Peak and peak-to-peak values are different quantities and should not be mixed into the same power equation.
Use the relationships to check RF hardware
A 50-ohm RF calculation connects voltage, current and power using the impedance relationship used by most amateur-radio coaxial systems and RF equipment. At a matched 50-ohm load, the familiar relationships P = V²/R and P = I²R provide a quick way to estimate RMS voltage and current from power. These values are useful when checking connectors, attenuators, dummy loads and matching networks, but the assumptions matter. A real antenna rarely presents a perfect 50-ohm resistance across a complete band, and reactive impedance changes the relationship between voltage, current and delivered real power. Peak RF voltage can also be substantially higher than the RMS value shown by a calculator. For station work, use the result to identify likely stress levels and then verify with suitable test equipment or manufacturer ratings. Do not assume that a calculated 50-ohm value means an antenna is actually matched; matching and impedance are separate questions that should be checked with an analyser or other appropriate instrument.