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Non-Inverting Op-Amp Gain

G=1+RfRinG = 1 + \frac{R_{f}}{R_{in}}

Worked example: 90 kΩ and 10 kΩ → gain 10 — press Try an example to run it live, then adjust anything.

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Non-Inverting Op-Amp Gain explained

RinRfG

Here the signal goes straight to the non-inverting input, and Rf with Rin form a divider that feeds a sample of the output back. Feedback forces that sample to equal the input, so the output must be larger by the divider's reciprocal: G = 1 + Rf/Rin. With 90 kΩ and 10 kΩ the gain is 10, in phase this time, and the input impedance is enormous — megohms to gigohms — because the signal only has to charge the op-amp's input capacitance.

That high input impedance is the reason this configuration dominates sensor front ends, where loading the source would corrupt the reading. The "one" cannot be removed: set Rf to zero and you get the unity-gain buffer, a follower with essentially infinite input and near-zero output impedance, which is the single most common op-amp circuit in existence. Attenuation, though, is impossible here — for gains below one, put a divider ahead of the buffer.

Non-Inverting Op-Amp Gain formula

G=1+RfRinG = 1 + \frac{R_{f}}{R_{in}}
Where
  • GG= Voltage gain
  • RfR_{f}= Feedback resistance (Ω)
  • RinR_{in}= Ground-leg resistance (Ω)

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