Op-Amp Calculator

For an inverting op-amp, the voltage gain is calculated as A = −Rf / Rin. The negative sign indicates that the output signal is 180° out of phase with the input signal. For example, if Rf = 100 kΩ and Rin = 10 kΩ, the gain is −10.

For a non-inverting op-amp, the voltage gain is A = 1 + Rf / Rin. The output is in phase with the input, and the gain is always greater than or equal to 1. With Rf = 100 kΩ and Rin = 10 kΩ, the gain is 11.

The output voltage is found using Vout = A × Vin, where A is the voltage gain and Vin is the input signal amplitude. For an inverting configuration the result will be negative (phase-inverted), while for non-inverting it will be positive.

A negative gain means the op-amp inverts the polarity of the input signal. If the input is +1 V and the gain is −10, the output will be −10 V. The magnitude of the gain still represents the amplification factor.

A non-inverting op-amp has a minimum gain of 1 (unity gain), which occurs when Rf = 0 or Rin is infinitely large. This unity-gain configuration is commonly used as a voltage buffer to isolate stages in a circuit.

You can enter resistor values in Ohms (Ω), kilohms (kΩ), or megohms (MΩ) using the unit selector next to each resistor field. The calculator automatically converts the values before computing the gain, so the ratio Rf/Rin remains consistent.

Gain in decibels is calculated as dB = 20 × log₁₀(|A|), where A is the linear voltage gain. A gain of 10 corresponds to 20 dB, a gain of 100 corresponds to 40 dB, and unity gain (1) equals 0 dB.

Yes. The gain and output voltage calculations apply to both DC and AC signals in the passband of the op-amp. For AC circuits you may also need to consider the op-amp's gain-bandwidth product, which limits the usable gain at higher frequencies.