How this calculation works
An ideal feedback amplifier’s resistor ratio sets signal gain, including its sign. That relation predicts the requested output, but a real device may not be able to provide it. This page keeps the ideal request separate from an externally supplied output interval.
Noninverting gain = 1 + Rf/Rg; inverting gain = −Rf/Rin; ideal output = gain × input; compare without clipping to entered boundsA worked example
A 90000-ohm feedback resistor and 10000-ohm grounded gain resistor give noninverting gain ten. A 0.2 V input requests two volts, leaving seven volts above a minus-five lower bound and three below plus five. Switching the same ratio to inverting mode gives gain minus nine and output minus 1.8 V. The plus-one term belongs to the noninverting topology, so it must not be copied into the inverting relation.
Good to know
Ideal static ground-referenced gain only; no offset reference, common-mode, rail swing, bandwidth, current, stability or device-selection model. Entered bounds are a comparison, not a safety certification. Validate the actual amplifier, supplies, signal range and load before building or operating a circuit.
Reference: Texas Instruments — noninverting gain relation (opens in a new tab) ↗
What this calculation answers
An ideal feedback amplifier’s resistor ratio sets signal gain, including its sign. That relation predicts the requested output, but a real device may not be able to provide it. This page keeps the ideal request separate from an externally supplied output interval.
Noninverting mode uses a resistor from the inverting node to ground. Inverting mode holds the noninverting input at ground and applies signal through the input resistor. A reference-offset circuit would need different equations.
The Loaded Wheatstone bridge output calculator supplies a signed differential signal. Amplifying that bridge with a real circuit also needs common-mode and topology checks beyond this simple ground-referenced gain model.
Use the right input conventions
Enter the resistor used in the chosen topology and ground-referenced input voltage. Positive resistor values are required; the calculation does not choose an op-amp or resistor power rating.
Allowed output bounds must come from appropriate device and operating data. They are not automatically equal to supply rails, and the page does not infer rail-to-rail capability or common-mode range from those numbers.
Interpret the result
The raw ideal output is not clipped to the interval. Signed headroom shows which bound is exceeded and by how much. Clipping it first would hide the size of the unsupported request.
Even an output inside those bounds does not establish bandwidth, slew rate, stability, input range or output-current suitability. This static ideal-gain comparison is one part of a larger circuit assessment.
Work through the example
A 90000-ohm feedback resistor and 10000-ohm grounded gain resistor give noninverting gain ten. A 0.2 V input requests two volts, leaving seven volts above a minus-five lower bound and three below plus five.
Switching the same ratio to inverting mode gives gain minus nine and output minus 1.8 V. The plus-one term belongs to the noninverting topology, so it must not be copied into the inverting relation.
Where the model stops
Ideal static ground-referenced gain only; no offset reference, common-mode, rail swing, bandwidth, current, stability or device-selection model.
Entered bounds are a comparison, not a safety certification. Validate the actual amplifier, supplies, signal range and load before building or operating a circuit.
A few questions, answered
Why keep an output beyond the bounds visible?
The unclipped value shows the ideal request and the signed shortfall instead of hiding it behind a clipped number.
Are output bounds just supply voltages?
Not necessarily. Actual allowed output swing depends on the device and operating conditions.