`dBm = 10*Log_10(V^2/(R*0.001mW))`

Enter a value for all fields

The dBm from Voltage and Impedance calculator compute the decibel milliwatts from the voltage and impedance.

INSTRUCTIONS:  Choose units and enter the following:

• (V) Voltage
• (R) Impedance

Decibel Milli-watts (dBm):  The calculator returns the power in decibel Milli-watts (dBm).

The Math / Science

The formula for dBm from voltage and impedance is:

           dBm = 10•Log₁₀(V²/(R•0.001mW))

where:

• dBm = decibel milliwatts
• V = voltage
• R = impedance

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Ohms Law Calculators

• Power (P) = I • V
• Power (P) = R • I²
• Power (P) = V² / R
• Volts (V) = I • R 
• Volts (V) = P / I
• Volts(V) = √(P • R)  
• Resistance (R) = V²/P
• Resistance (R) = P / I² 
• Resistance (R) =  V / I 
• Current (I) = V / R
• Current (I) = P / V 
• Current (I) = √(P/R)