dBm to Voltage Calculator
Convert RF power (dBm) to RMS, peak, and peak-to-peak voltage across a known load impedance.
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Inputs
Live
Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
V(rms) = √(P(W) × R), where P(W) = 10^((P(dBm) - 30) / 10)This formula is used to calculate antenna parameters for dbm to voltage calculator.
Overview
The dBm to Voltage Calculator converts RF power levels expressed in decibel-milliwatts (dBm) into equivalent RMS voltage (V_rms), Peak voltage (V_pk), Peak-to-Peak voltage (V_pp), and dBmicroV across any specified characteristic load impedance (R, typically 50 ohms or 75 ohms).
Input Guide
Enter Power exactly as shown on the calculator. Confirm every unit, selected option, and decimal position before calculating so the dbm to voltage result matches the intended rf conversion design case.
Output Guide
The output section reports RMS Voltage, RMS Voltage (mV), Peak Voltage (Vpk), Peak-to-Peak Voltage (Vpp), Voltage Level (dBµV), Power (Linear) for the values you entered. Use these values as design targets, then compare them with available space, component limits, feed system behavior, installation environment, and measured performance before finalizing the design.
How This Calculator Works
The dBm to Voltage applies V(rms) = √(P(W) × R), where P(W) = 10^((P(dBm) - 30) / 10) to the entered values. Convert RF power (dBm) to RMS, peak, and peak-to-peak voltage across a known load impedance. Use the result as a first-pass rf conversion target, then validate it against losses, tolerances, mounting, nearby conductors, feed-line effects, and measurement conditions.
Design Notes
Power in dBm is referenced to 1 milliwatt (0 dBm = 1 mW). To convert power in dBm to RMS voltage, first convert dBm to linear Watts: P_Watts = 10^(P_dBm - 30)/10. RMS voltage is then calculated using Ohm's Law: V_rms = sqrtP_Watts * R. For a standard 50 ohms system, 0 dBm corresponds to exactly 0.2236 V_rms (223.6 mV_rms or 632.5 mV_pp) and 107 dBmicroV.
Build and Tuning Notes
When connecting RF signal generators or power amplifiers to oscilloscopes and spectrum analyzers, always verify system load impedance (50 ohms vs 75 ohms). Measuring a 50 ohms source with a high-impedance (1 Mohms) oscilloscope probe doubles the displayed peak-to-peak voltage due to unloaded signal reflection (+6 dB voltage scaling). Ensure proper inline 50 ohms feedthrough terminations are installed for high-frequency measurements.
Inputs used by this calculator
- Power — use dBm.
- Load Impedance (R) — use ohms.
Frequently Asked Questions
How do I convert 0 dBm to RMS voltage in a 50 ohms system?
0 dBm equals 1 mW (0.001 W). In a 50 ohms load, V_rms = sqrt(0.001 * 50) = sqrt(0.05) approximately 0.2236 V_rms (223.6 mV_rms).
What is the relationship between Vrms, Vpeak, and Vpp for sinusoidal RF signals?
For pure sinusoidal AC signals, Peak Voltage is V_pk = V_rms * sqrt(2) approximately 1.414 * V_rms. Peak-to-Peak voltage is V_pp = 2 * V_pk approximately 2.828 * V_rms.
How does load impedance (e.g., 50 ohms vs 75 ohms) change the voltage calculation?
Voltage depends on load resistance (V = sqrt(P * R)). For 0 dBm (1 mW), a 50 ohms load develops 223.6 mV_rms, whereas a 75 ohms load develops 273.9 mV_rms.
How is dBµV calculated from RMS voltage?
dBmicroV expresses RMS voltage relative to 1 microvolt (1 microV): dBmicroV = 20 * log_10(V_rms / 1microV) = 20 * log_10(V_rms * 10^6).
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.