Non-Inverting Op-Amp Gain Calculator Formula

Understand the math behind the non-inverting op-amp gain calculator. Each variable explained with a worked example.

Use the Non-Inverting Op-Amp Gain Calculator

Formulas Used

Voltage Gain

gain = 1 + rf_kohm / r1_kohm

Gain (dB)

gain_db = 20 * log10(1 + rf_kohm / r1_kohm)

Output Voltage

v_output = (1 + rf_kohm / r1_kohm) * v_input

Variables

VariableDescriptionDefault
r1_kohmGround Resistor (R1)(kΩ)10
rf_kohmFeedback Resistor (Rf)(kΩ)90
v_inputInput Voltage(V)1

How It Works

Non-Inverting Op-Amp Configuration

Formula

Gain = 1 + Rf / R1

V_out = (1 + Rf / R1) x V_in

Output is in phase with input. Minimum gain is 1. Input impedance is very high, set by the op-amp input stage.

Worked Example

R1 = 10k, Rf = 90k, input signal is 1 V.

r1_kohm = 10rf_kohm = 90v_input = 1
  1. 01Gain = 1 + 90 / 10 = 10 V/V
  2. 02Gain in dB = 20 x log10(10) = 20 dB
  3. 03V_out = 10 x 1 = 10 V

Frequently Asked Questions

What is the minimum gain?

Minimum gain is 1 (unity) when Rf = 0 or R1 is infinite. This is the voltage follower configuration.

Why choose non-inverting over inverting?

Non-inverting offers very high input impedance, no phase inversion, and a minimum gain of 1.

How does it compare to a voltage follower?

A voltage follower is a special case with gain = 1 (Rf = 0). It buffers signals without amplification.

Ready to run the numbers?

Open Non-Inverting Op-Amp Gain Calculator