Op-Amp Gain Calculator

Choose a configuration and enter resistor values to compute gain and output voltage instantly. Includes show-work steps and clean resistor-ratio math.

How to Use

  1. Select an op-amp configuration (Inverting, Non-Inverting, or Voltage Follower).
  2. Enter resistor values (Rin/Rf or Rg/Rf depending on mode).
  3. Optional: enter Vin to estimate Vout from the ideal closed-loop gain.
  4. Open “Show Work” to see the exact formula and substitutions.
Amplifier Lab View
Visual feedback: configuration + computed gain and estimated output.
Mode
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Gain (Av)
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Vin
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Vout
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Status: —
Op-Amp − + Vin Vout Rf Rin / Rg Visual shows a typical feedback network. Mode selection updates labels.
Inputs & Settings
Choose a configuration, then enter resistor values. Optional Vin calculates ideal Vout.
This tool uses ideal closed-loop gain equations (no saturation/bandwidth modeling).
Optional. If blank, Vout is not computed.
Inverting uses Rin. Non-inverting uses Rg (to ground).
Rf is the feedback resistor from output to the inverting input node.
Used only for “Solve Rf” or “Solve Rin/Rg”. For inverting, magnitude is used; sign is implied by mode.
Optional warning only (does not clamp). Useful for a quick “rail” sanity check.
Show Work (step-by-step)
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Work is shown in base units (V and Ω). Gain is unitless. dB uses 20·log10(|Av|).

Gain Formulas

Inverting: Av = −(Rf / Rin)

Non-Inverting: Av = 1 + (Rf / Rg)

Voltage Follower: Av = 1

  • Output estimate: Vout = Av × Vin (ideal closed-loop)
  • Gain in dB: Gain(dB) = 20·log10(|Av|)
Notes: Real op-amps are limited by supply rails, output current, and bandwidth. This tool focuses on closed-loop resistor math.

FAQ

Why is inverting gain negative?

In an inverting amplifier, the output is 180° out of phase with the input, so the gain sign is negative.

What resistor values should I choose?

Common starting points are in the 1kΩ–100kΩ range. Too low wastes current; too high can increase noise and bias-current error.

Why doesn’t my real circuit match exactly?

Real op-amps have finite open-loop gain, bandwidth limits, input bias currents, and output swing limits. Gain can droop at higher frequency.

Does this include saturation/clipping?

No—this tool can warn if you enter an optional Vout limit, but it does not model rails or clipping.

Tool Info

Last updated:

Updates may include additional presets, improved validation, and more resistor target options.