Op-Amp Gain Calculator

Analyze the three classic op-amp feedback circuits — inverting, non-inverting, and difference (differential) amplifiers. Enter the feedback and input resistors to get the closed-loop voltage gain (as a ratio and in dB), and optionally add the input voltage(s) to get the output voltage and an optional gain-bandwidth product to find the small-signal bandwidth. Inverting gain is −Rf/Rin, non-inverting is 1 + Rf/Rg, and the difference amplifier subtracts its two inputs. Useful for sensor signal conditioning, audio preamps, instrumentation and active filter stages. Pure arithmetic — ideal op-amp equations that assume infinite open-loop gain and input impedance; real op-amps add input bias current, offset voltage, slew-rate limits and a roll-off that pushes the bandwidth below the GBW estimate, so check the datasheet and leave headroom for the rails. Everything runs locally in your browser.