Op-Amp Gain Calculator

Setting op-amp gain from resistor values — or the reverse — comes up constantly during analog front-end bring-up. This calculator covers both inverting and non-inverting configurations, so you can size feedback resistors for a target gain or check the gain an existing circuit on a board is actually delivering.

Op-Amp Gain

Inverting and non-inverting configurations

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Configuration

Rf (feedback)

Rg (to ground)

Vin

Gain-bandwidth

V+ (positive rail)

Optional — leave blank to skip clipping checkV− (negative rail)

Gain (V/V)

11.0000

Gain (dB)

20.83 dB

Vout

1.10 V

Noise gain

11.000

Closed-loop BW

90.9 kHz

Formula

G = 1 + \frac{R_{f}}{R_{g}}

V_{out} = G \cdot V_{in}

G_{dB} = 20 \cdot \log_{10} | G |

G_{n} = 1 + \frac{R_{f}}{R_{g}}

BW = \frac{GBW}{G_{n}}

Ideal op-amp: the two inputs sit at the same voltage and draw no current, so the resistors alone set the gain.

G = closed-loop gain (V/V)
R_f = feedback resistor, from the output to the − input (Ω)
R_g = resistor from the − input to ground (Ω)
G_n = noise gain, the gain that sets bandwidth
GBW = gain-bandwidth product from the datasheet (Hz)
BW = closed-loop bandwidth (Hz)

Non-inverting gain never goes below 1×. Input impedance is the op-amp's own, so source loading is negligible.