Calculators · Analog gain
Op amp gain
LiveCalculate inverting, non-inverting, and simple differential gain from resistor values.
Size resistor ratios and sanity-check amplifier output levels.
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Calculator guide
Op amp gain formulas and practical checks
Formulas, examples, and practical notes for using the result with confidence.
Overview
An op amp is a signal helper with a strong opinion about feedback. Arrange two resistors around it and you can make a small sensor signal larger, flip its polarity, or amplify the difference between two voltages.
This op amp gain calculator sizes the ideal resistor ratio and estimates the output for non-inverting, inverting, and basic differential circuits. The maths gets you started; the op amp datasheet decides whether the real device can keep up.
Current example
Enter valid values above and this example will update with the calculator state.
Pick the signal path first
The same resistor values mean different things depending on the circuit topology.
A non-inverting amplifier keeps the input polarity and has a minimum gain of 1. An inverting amplifier flips polarity and can have gains below or above 1 in magnitude.
A basic differential amplifier measures the difference between two signals, but good accuracy requires matched resistor ratios and attention to common-mode range.
Non-inverting
Keeps signal polarity and presents a high input impedance. Great for sensor buffering and gain.
Inverting
Flips polarity and makes summing or attenuation easy around a virtual-ground node.
Differential
Amplifies the difference between two inputs when resistor ratios are accurately matched.
Let the feedback ratio set the gain
Feedback ratio controls the ideal closed-loop gain.
The calculated gain is ideal. Real op amps have finite bandwidth, input offset, output swing limits, noise, input bias current, and stability requirements.
High resistor values reduce current draw but increase noise and bias-current errors. Very low resistor values load the op amp output and waste power.
Non-inverting gain
Inverting gain
Sensor gain example
A non-inverting stage with Rin = 10 kΩ and Rf = 40 kΩ has a gain of 5. A 0.5 V sensor signal ideally becomes 2.5 V.
Check whether the output has room to move
The output estimate is only valid if the op amp can swing to that voltage.
Check the expected output against the supply rails. Many op amps cannot output exactly to ground or the positive rail, especially under load.
For AC signals, also check slew rate and gain bandwidth product. A gain that works at DC may not work at the frequency you care about.
Useful places to add gain
Feedback gain blocks are used in sensing, filtering, and signal conditioning.
Use this calculator for sensor gain stages, audio preamps, level scaling, photodiode support circuits, and instrumentation front ends.
When precision matters, choose resistor tolerances and op amp specifications together rather than treating the ideal gain as guaranteed.
Sensor scaling
Amplify small sensor voltages into an ADC-friendly range.
Audio gain
Set low-noise gain while checking output swing and bandwidth.
Signal inversion
Create a controlled negative gain or summing node.
When ideal gain meets a real op amp
Most op amp calculator errors come from ignoring non-ideal op amp limits.
The resistor ratio does not guarantee the output can reach the calculated value. Supply voltage, input common-mode range, output swing, load current, and frequency all matter.
For differential circuits, unmatched resistor ratios reduce common-mode rejection and can turn supply or ground noise into output error.
Assumptions and limits
- Results are design estimates, not a substitute for datasheets, measurements, safety approvals, or engineering review.
- Component tolerance, temperature, supply variation, and real loading can move the final circuit away from the ideal calculation.
- Calculator results are estimates for design and learning. Verify values against datasheets, tolerances, temperature, load behaviour, and safety requirements before using them in a real circuit.
Licensing
Calculator copy, equations, and generated visuals are provided for learning and design-reference use on Kobee unless a specific licence is shown.
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