Operational amplifiers can be designed to have infinite gain in practical applications.

In theory, an ideal operational amplifier is described as having an infinite open‑loop gain, meaning any tiny difference between its inputs is amplified without bound. In practice, however, real op‑amps have very high but finite open‑loop gains—often on the order of 100 dB or 100,000:1—and their gain decreases at higher frequencies. Because the gain is finite, designers use negative feedback to force the amplifier to behave as if it had the desired closed‑loop gain, which is stable and predictable. For example, a 10‑volt input applied to a 10‑fold feedback network will produce a 100‑volt output only if the op‑amp’s open‑loop gain is much larger than the closed‑loop gain; otherwise the output will saturate or distort. Thus, while the ideal op‑amp model assumes infinite gain, practical op‑amps rely on high but finite gain and feedback to achieve usable performance.