Op Amp Gain
Calculate inverting and non-inverting op-amp voltage gain from resistor values with dB conversion. Free op-amp gain calculator with charts.
About This Calculator
The Op Amp Gain Calculator computes the voltage gain of operational amplifier circuits for both inverting and non-inverting configurations. Whether you are designing audio amplifiers, sensor signal conditioning circuits, active filters, or instrumentation amplifiers, this tool helps you quickly determine the gain from your resistor values and understand the circuit behavior.
The calculator uses the standard op-amp gain formulas. For the inverting configuration, the voltage gain is Av = -Rf / Rin, where the negative sign indicates a 180° phase inversion between input and output. For the non-inverting configuration, the voltage gain is Av = 1 + Rf / R1, where the output remains in phase with the input. Both formulas assume an ideal op-amp with negative feedback, where the differential input voltage is driven to zero (virtual short concept). The calculator also converts the absolute voltage gain to decibels using the formula Gain(dB) = 20 × log₁₀(|Av|).
For example, an inverting amplifier with Rin = 1 kΩ and Rf = 10 kΩ produces a gain of -10 (20 dB). A non-inverting amplifier with the same resistor values produces a gain of 11 (20.8 dB). The calculator presents results with a breakdown of resistor values and gain in multiple formats, plus a bar and pie chart for visual comparison of the circuit parameters.
Regional Notes
Op-amp circuits are universal in electronics design worldwide. Resistor values are measured in ohms (Ω) independent of currency or region. Standard resistor series (E12, E24, E48, E96) are used globally, though availability of specific values may vary. When building circuits, select the nearest standard resistor value from your local supplier's inventory. The gain formulas and decibel calculations are identical across all regions as they are based on fundamental electronic principles.
Frequently Asked Questions
What is an op-amp (operational amplifier)?
An operational amplifier (op-amp) is an electronic device that amplifies the difference between two input voltage signals. Op-amps are the basic building blocks of analog electronic circuits, used for mathematical operations like addition, integration, differentiation, and comparison, as well as signal filtering and conditioning.
How do you calculate the gain of an inverting op-amp?
For an inverting op-amp, the voltage gain is calculated as Gain = -Rf / Rin, where Rf is the feedback resistance and Rin is the input resistance. The negative sign indicates the output signal is 180 degrees out of phase with the input signal.
How do you calculate the gain of a non-inverting op-amp?
For a non-inverting op-amp, the voltage gain is calculated as Gain = 1 + Rf / R1, where Rf is the feedback resistance and R1 is the resistance between the inverting terminal and ground. The output signal remains in phase with the input signal.
What is the difference between inverting and non-inverting op-amp configurations?
In an inverting op-amp, the input signal is applied to the inverting terminal through a resistor, and the output is inverted (180° phase shift). In a non-inverting op-amp, the input signal is applied directly to the non-inverting terminal, and the output is in phase (0° shift). The non-inverting configuration always has a gain of at least 1, while the inverting configuration can have gains below 1.
What are the characteristics of an ideal op-amp?
An ideal op-amp has infinite input impedance, zero output impedance, infinite voltage gain, and infinite bandwidth. In practical op-amps, these parameters approach ideal values but have real-world limitations that affect circuit design.
What are common applications of op-amps?
Op-amps are widely used as signal amplifiers in audio equipment, sensors, and instrumentation. They perform mathematical operations in analog computers, serve as active filters in signal processing, work as comparators in voltage detection circuits, and function as converters between current and voltage signals.
How do I convert voltage gain to decibels (dB)?
Voltage gain in decibels is calculated as Gain(dB) = 20 × log₁₀(|Gain|). For example, a voltage gain of 10 corresponds to 20 dB, a gain of 100 corresponds to 40 dB, and a gain of 2 corresponds to approximately 6 dB.
How should I choose resistor values for an op-amp circuit?
Choose resistor values in the range of 1 kΩ to 100 kΩ for most op-amp circuits. Avoid very low values (under 100 Ω) to prevent excessive current draw, and avoid very high values (over 1 MΩ) to minimize noise and offset voltage effects. Use standard resistor values from the E12 or E24 series for practical implementations.