Op Amp Gain Calculator
Calculate op-amp gain and check it against the gain-bandwidth product.
About Op Amp Gain Calculator
Gain and bandwidth trade directly against each other: their product is fixed by the device. A non-inverting stage cannot have a gain below one, while an inverting stage can attenuate. A 1 MHz op-amp configured for a gain of 47 has only about 21 kHz of bandwidth, which catches out many first designs.
Formula
Op Amp Gain
Inverting: A = −R_f ÷ R_in; non-inverting: A = 1 + R_f ÷ R_in; bandwidth = GBW ÷ gain
- GBW
- Gain-bandwidth product, a fixed figure for the device
- closed-loop gain
- Gain set by the feedback network
Worked example
With the default values below, Op Amp Gain Calculator returns Closed-Loop Gain of -47.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Input resistorminimum 0.01 ohm
- 1,000 ohm
- Feedback resistorminimum 0.01 ohm
- 47,000 ohm
- Gain-bandwidth productminimum 1 Hz
- 1,000,000 Hz
- Configurationone of Inverting, Non-inverting
- Inverting
Results
- Closed-Loop Gain
- -47.0000
- Gain
- 33.442 dB
- Available Bandwidth
- 21,276.60 Hz
- Input Impedance
- Equal to the input resistor
- Output Polarity
- Inverted relative to the input
Step by step
- 1Values used
- 2Op Amp Gain
- 3Closed-Loop Gain= -47.0000
- 4Gain= 33.442 dB
- 5Available Bandwidth= 21,276.60 Hz
- 6Input Impedance= Equal to the input resistor
- 7Output Polarity= Inverted relative to the input
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Op Amp Gain calculated?
Inverting: A = −R_f ÷ R_in; non-inverting: A = 1 + R_f ÷ R_in; bandwidth = GBW ÷ gain Gain and bandwidth trade directly against each other: their product is fixed by the device. A non-inverting stage cannot have a gain below one, while an inverting stage can attenuate.
Why does Op Amp Gain matter?
A 1 MHz op-amp configured for a gain of 47 has only about 21 kHz of bandwidth, which catches out many first designs.
What values do I need to enter?
This calculator takes 4 inputs: Input resistor, Feedback resistor, Gain-bandwidth product, Configuration. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.