Op-Amp Gain Calculator
Inverting and non-inverting op-amp gain, dB and resistor values.
About this tool
Choose inverting or non-inverting, then enter the feedback and input resistors, the input voltage and the supply. The tool shows gain, dB, output voltage and a clipping warning. Enter a target gain to get the nearest standard resistor.
Op-amp gain formulas
With negative feedback, an op-amp's gain is set by two resistors. The non-inverting amplifier feeds the signal to the + input: G = 1 + Rf ÷ Rg, so it is always at least 1, and its input impedance is very high. 100 kΩ and 10 kΩ give a gain of 11 (20.8 dB). The inverting amplifier feeds the signal through Rin to the − input: G = −Rf ÷ Rin, which flips the signal, and the circuit's input impedance equals Rin. 100 kΩ and 10 kΩ give −10 (20 dB). Gain in decibels is 20 log₁₀|G|. The output can't exceed the supply: most op-amps swing to within 1–2 V of the rails, so the tool warns when the output would clip. The design helper calculates the ideal feedback resistor for a gain and picks the nearest E24 value. Honest limits: these are ideal formulas. Gain-bandwidth product limits gain at higher frequencies (a 1 MHz part at gain 100 only reaches about 10 kHz), and offset and bias currents matter with large resistors. The voltage divider calculator and the decibel calculator are related.
Frequently asked questions
What is the gain of a non-inverting amplifier?
1 + Rf ÷ Rg. With Rf = 100 kΩ and Rg = 10 kΩ, the gain is 11.
What is the gain of an inverting amplifier?
−Rf ÷ Rin. With Rf = 100 kΩ and Rin = 10 kΩ, the gain is −10.
How do I convert gain to dB?
Multiply the base-10 logarithm of the gain's magnitude by 20. A gain of 10 is 20 dB.
Why is my op-amp output clipping?
The required output exceeds what the op-amp can swing within its supply rails. Reduce the gain or increase the supply.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.