Calculate amplifier input voltage, output voltage, or gain by choosing Solve for, entering the two known values, and selecting Calculate. V, mV, and kV units are supported.

Multiply input voltage by linear voltage gain. Gain is a ratio, not a dB value; negative gain represents inversion.

For example, 8 means eight times the input. Use a negative value for inversion; do not enter dB.

Amplifier Voltage Formula

The amplifier voltage calculation is based on the relationship between input voltage, amplifier gain, and output voltage.

Vₒut = Vᵢn × Aᵥ
Aᵥ = Vₒut / Vᵢn
Vᵢn = Vₒut / Aᵥ
  • V_out = amplifier output voltage
  • V_in = input or source voltage
  • A_v = voltage gain of the amplifier, unitless

The calculator uses the first formula when you enter input voltage and gain to find output voltage. It uses the second formula when you enter input and output voltage to find gain. It uses the third formula when you enter output voltage and gain to find the required input voltage.

Voltage inputs are converted to volts for the calculation. For voltage results, choose the Answer voltage unit. Supported voltage units are millivolts, volts, and kilovolts.

Voltage Unit Conversions

Unit Symbol Value in volts
Millivolt mV 0.001 V
Volt V 1 V
Kilovolt kV 1,000 V

Common Gain Values and Output Examples

Input voltage Gain Output voltage Meaning
100 mV 2 200 mV Voltage is doubled
100 mV 10 1 V Small signal is amplified to volts
1 V 5 5 V Output is five times the input
2 V 0.5 1 V Gain below 1 reduces voltage

Example Problems

Example 1: Calculate output voltage

You have an input voltage of 250 mV and an amplifier gain of 8.

Vₒut = Vᵢn × Aᵥ

Convert the input voltage to volts:

250 mV = 0.25 V

Apply the gain:

Vₒut = 0.25 × 8 = 2 V

The output voltage is 2 V.

Example 2: Calculate amplifier gain

You have an input voltage of 0.5 V and an output voltage of 12 V.

Aᵥ = Vₒut / Vᵢn
Aᵥ = 12 / 0.5 = 24

The amplifier gain is 24.

FAQ

Is amplifier gain measured in volts?

No. Voltage gain is unitless because it is a ratio of output voltage to input voltage. For example, if an amplifier outputs 10 V from a 2 V input, the gain is 5.

Can amplifier gain be less than 1?

Yes. A gain magnitude below 1 reduces voltage magnitude; a negative gain indicates inversion. For example, a gain of 0.5 changes a 4 V input into a 2 V output.

Why does the calculator require exactly two values?

Choose the unknown in Solve for and enter the other two values. Zero divisors can make an inverse solution impossible or nonunique; the calculator explains these cases. The relationship assumes ideal linear operation and does not predict clipping or supply limits.