Voltage Gain Calculator (with Examples)

This tool calculates the voltage gain for a specified input and output voltage.

Calculator

Enter the input and output voltage. Use the drop down menu to select the appropriate units.


	

			

		

						

				

				

                

			

			
						

		

		






Example Calculations





For input of 5 Volt and output 15 Volt, the linear voltage gain is 3. Expressed in deciBels, it is 10 dB. 





Background





Voltage gain is a measure of how much an amplifier increases the amplitude of an input voltage signal. It is expressed as a ratio of the output voltage to the input voltage and is often specified in decibels (dB). The voltage gain Av can be calculated using the following formula:





Av = 20*Log⁡10(Vout/Vin)





Where:





    

  • Av is the voltage gain
    • 




  • Vout is the output voltage
    • 




  • Vin​ is the input voltage
    • 






If the voltage gain is given without the logarithmic scale, it can be expressed as a simple ratio:





Av = Vout/Vin





Voltage gain is a fundamental parameter in the characterization of amplifiers, which are electronic devices designed to increase the strength of a signal. It describes the amplification capability of the amplifier for a given input signal. 





Different types of amplifiers, such as operational amplifiers (op-amps), audio amplifiers, and radio frequency amplifiers, may have different voltage gain specifications based on their intended applications.





It’s important to note that while voltage gain is a crucial parameter, it is not the only factor to consider when evaluating an amplifier’s performance. 





Factors like frequency range, input/output impedance, Voltage Standing Wave Ratio (VSWR), and third order intermodulation (IP3) also play a significant role in determining the suitability of an amplifier for a specific application.





VSWR impacts mismatch at the input to an amplifier – use this tool to understand the relationship between VSWR and reflected power. As the VSWR increases, so also does the reflected power. This implies that it’s a poorly designed amp. 





In this calculator it is assumed that the input and output impedance is the same. This is not always true. In RF circuits an amp might have to be matched to 50 ohm for instance, to optimize its performance.





How is Voltage Gain measured practically?





Voltage gain can be determined by using an oscilloscope to measure both input and output root-mean-square voltages. 





Siglent Technologies SDS1202X-E 200 mhz Digital Oscilloscope 2 Channels, Grey





 Modern scopes will provide the RMS voltage. However an older scope might only provide the peak-to-peak voltage. Use this calculator to find the RMS voltage from Vpp.





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