Op-Amp Gain Calculator — Inverting & Non-Inverting
Enter your feedback resistor (Rf), input resistor (Rin) and input voltage for either an inverting or non-inverting op-amp circuit, and instantly see the closed-loop voltage gain, output voltage, and gain in decibels.
Configuration
kΩ
kΩ
V
Non-inverting configuration — output is in phase with input
- 1
Rf ÷ Rin ratio
100 ÷ 10 = 10 - 2
Voltage gain (non-inverting)
1 + 10 = 11
How does this calculator work?
Op-amp closed-loop gain depends only on two resistors: non-inverting gain = 1 + Rf/Rin; inverting gain = –Rf/Rin. Multiply gain by Vin to get Vout. Convert to dB with 20 × log₁₀|Gain|. The negative sign in inverting mode means the output is phase-inverted, not attenuated.
Formula
How this is calculated
An operational amplifier with negative feedback sets its gain almost entirely by the external resistors, not by the open-loop gain of the chip itself (typically 100 000+). In the non-inverting configuration the signal enters the + input and the feedback network from output to – input sets the closed-loop gain to 1 + Rf/Rin. In the inverting configuration the signal enters through Rin at the – input; the virtual-ground principle means the gain is –Rf/Rin (the minus sign indicates a 180° phase inversion).
Gain in decibels is 20 × log₁₀|Gain|, a logarithmic scale used in audio and RF work. For example, a voltage gain of 10 equals 20 dB. Any self-consistent resistance unit works — if both Rf and Rin are in kΩ the ratio (and therefore the gain) is the same as if both were in Ω.
This calculator assumes ideal op-amp behaviour: infinite open-loop gain, infinite input impedance, zero output impedance, zero offset voltage and unlimited bandwidth. Real op-amps have finite gain-bandwidth product, input bias currents and supply-rail saturation limits that cap the actual output swing — consult your op-amp datasheet for those constraints.
Frequently asked questions
The closed-loop voltage gain of a non-inverting amplifier is 1 + Rf/Rin. Because the signal enters the non-inverting (+) input the output is in phase with the input, so the gain is always ≥ 1. Setting Rf = 0 (short) and Rin = ∞ (open) gives unity-gain buffer with gain = 1.
Gain = –Rf/Rin. The negative sign means the output is 180° out of phase with the input — when Vin goes positive, Vout goes negative. The magnitude |Gain| tells you by how much the signal is amplified. A gain of –10 means the output is 10× the amplitude and inverted.
Power gain uses 10 log₁₀ because power ∝ voltage². Voltage gain uses 20 log₁₀ so that a doubling of voltage (3 dB power gain) also reads as approximately 6 dB in voltage terms, keeping the scales consistent. The absolute magnitude is used so that an inverting gain of –10 still gives +20 dB.
Also known as
TG we-Calculate Editorial Team. (2026). Op-Amp Gain Calculator — Inverting & Non-Inverting [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/op-amp-gain-calculator
TG we-Calculate Editorial Team. "Op-Amp Gain Calculator — Inverting & Non-Inverting." TG we-Calculate. 2026. https://we-calculate.com/calculator/op-amp-gain-calculator.
TG we-Calculate Editorial Team, "Op-Amp Gain Calculator — Inverting & Non-Inverting," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/op-amp-gain-calculator
@misc{wecalculate_op_amp_gain_calculator, title = {Op-Amp Gain Calculator — Inverting & Non-Inverting}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/op-amp-gain-calculator}}, year = {2026}, note = {TG we-Calculate} }
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