How this calculator works
Negative feedback makes the ideal op-amp inputs nearly equal in voltage. The resistor ratio then sets closed-loop voltage gain. Inverting circuits reverse polarity; non-inverting circuits add unity gain. Finite open-loop gain, gain-bandwidth product, output swing and slew rate limit real operation.
Formula
Inverting: Av = -Rf/Rin. Non-inverting: Av = 1 + Rf/Rg. Gain magnitude in dB = 20 log10(|Av|).
Worked example
With a 10 kilohm input resistor and 100 kilohm feedback resistor, inverting gain is -10 and non-inverting gain is 11.
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Frequently asked questions
Why is inverting gain negative?
The output changes in the opposite direction from the input, corresponding to a polarity reversal.
Can non-inverting gain be below one?
Not with the standard two-resistor circuit and positive resistances. A voltage follower has gain one.
Does the result include frequency response?
No. Consult the amplifier gain-bandwidth and stability specifications for the chosen gain and load.