Op-amp gain calculator — inverting / non-inverting / differential

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Configuration

R1 (input to inverting pin)Ohms — from the input to the summing nodeR2 (feedback resistor)Ohms — from the output back to the summing nodeInput voltage (V_in)Volts — to see the output swing

Closed-loop gain

Reverse: target gain → R2

Gain (×)

1 + R2/R1 — output in phase

Gain

20·log10(|gain|)

9.54 dB

Output voltage

gain × V_in

0.3 V

Quick reference

×1 buffer

R2 = 0, any R1 (unity gain, output follows input)

×2

R2 = R1, e.g. 10k + 10k

×10

R2 = 9×R1, e.g. 90k + 10k

×11

R2 = 10×R1, e.g. 100k + 10k

About the model

These are the closed-loop gain formulas for an ideal op-amp: infinite open-loop gain, infinite input impedance and zero output impedance, so the feedback network alone sets the gain. Real op-amps are limited by the gain-bandwidth product (GBW): gain × bandwidth ≤ GBW, so a high-gain stage is also a low-bandwidth one — and the input bias current and offset voltage shift the output by a few millivolts that you should account for in precision designs.

For the parts themselves: operational amplifiers and precision resistors carry the GBW and tolerance specs this math assumes.

Browse related parts:

operational amplifiers resistor kits precision resistors

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