How to Use Operational Amplifier Gain Calculator
- Choose the amplifier topology: inverting, non-inverting, or differential.
- Enter resistor values using Ω, kΩ, or MΩ. The selected unit applies to the resistor fields.
- Enter Vin for inverting and non-inverting stages, or V1 and V2 for the differential stage.
- Set the supply rail limit to check whether the ideal output magnitude is larger than the available output swing.
Formula & Theory - Operational Amplifier Gain Calculator
Inverting: Av = -Rf / Rin
Non-inverting: Av = 1 + Rf / Rg
Vout = Av × Vin
Differential: Vout = (Rf / Rin) × (V2 - V1)
Gain(dB) = 20 log10(|Av|)The inverting amplifier has a negative gain, so the output is ideally 180 degrees out of phase with the input. The non-inverting amplifier gain starts at 1 and stays in phase.
The differential equation assumes matched resistor ratios. If the real circuit uses unmatched resistor pairs, common-mode rejection and gain accuracy will be worse than the ideal calculation.
The rail check is an ideal warning, not a full output-swing model. Real op-amps also have input common-mode limits, output headroom, slew rate, bandwidth, and load-current constraints.
Use Cases for Operational Amplifier Gain Calculator
- Selecting feedback resistors for signal conditioning stages.
- Estimating whether a sensor signal will clip against the op-amp supply rails.
- Comparing linear gain and dB gain in audio or instrumentation circuits.
- Explaining phase inversion in an inverting op-amp configuration.