Op-Amp Non-Inverting Gain Calculator

Find the closed-loop gain and output voltage of a non-inverting op-amp circuit from its feedback and ground resistors.

🔌 Op-Amp Non-Inverting Gain Calculator
Input voltage (Vin)0.50 V
V
-10 V10 V
Ω
Ω
Output voltage (Vout)
—
Gain (Av)
—
Input impedance (Zin)
—
Step-by-step working

🔌 What is the Op-Amp Non-Inverting Gain Calculator?

The Op-Amp Non-Inverting Gain Calculator finds the closed-loop voltage gain and output voltage of a non-inverting operational amplifier circuit, the other fundamental op-amp amplifier topology alongside the inverting configuration, from its feedback resistor Rf and ground resistor Rin.

Electronics designers use this calculation to build high-input-impedance amplifier front ends for sensors and instrumentation, design voltage-follower buffers that isolate a source from a load without loading it down, and set precise, always-positive gain values for signal conditioning circuits.

A common point of confusion is thinking the gain can be reduced below 1 by choosing small resistor values. Because the formula is Av = 1 + Rf/Rin, the gain is mathematically bounded below by 1, reached only in the limiting case Rf = 0 (the voltage follower), and this calculator flags that case automatically.

This calculator applies the ideal op-amp approximation (infinite open-loop gain, essentially infinite input impedance, zero output impedance), which closely matches real op-amp behavior within their bandwidth and output swing limits.

📐 Formula

Av = 1 + Rf / Rin      Vout = Av × Vin
Av = closed-loop voltage gain (dimensionless, always ≥ 1)
Rf = feedback resistor (Ω), Rin = resistor from inverting input to ground (Ω)
Special case: Rf = 0 → Av = 1 (voltage follower / buffer)
Example: Vin = 0.5 V, Rin = 1,000 Ω, Rf = 9,000 Ω → Av = 10, Vout = 5 V.

📖 How to Use This Calculator

Steps

1
Enter the input voltage. Type Vin, the signal voltage applied to the non-inverting input.
2
Enter the ground resistor. Type Rin, the resistor connecting the inverting input to ground.
3
Enter the feedback resistor. Type Rf, the resistor connecting the output back to the inverting input. Use 0 for a unity-gain buffer.

💡 Example Calculations

Example 1 — 10x Non-Inverting Gain Stage

Vin = 0.5 V, Rin = 1,000 Ω, Rf = 9,000 Ω

1
Av = 1 + 9,000 / 1,000 = 10
2
Vout = 10 × 0.5 V = 5 V
Av = 10, Vout = 5 V
Try this example →

Example 2 — Voltage Follower (Unity-Gain Buffer)

Vin = 1 V, Rin = 10,000 Ω, Rf = 0 Ω

1
Av = 1 + 0 / 10,000 = 1 (buffer)
2
Vout = 1 × 1 V = 1 V
Av = 1, Vout = 1 V
Try this example →

Example 3 — Moderate Gain Stage

Vin = 2 V, Rin = 2,200 Ω, Rf = 6,800 Ω

1
Av = 1 + 6,800 / 2,200 = 4.0909
2
Vout = 4.0909 × 2 V = 8.1818 V
Av = 4.0909, Vout = 8.1818 V
Try this example →

❓ Frequently Asked Questions

What is the formula for non-inverting op-amp gain?+
The closed-loop gain of a non-inverting amplifier is Av = 1 + Rf/Rin, where Rf is the feedback resistor from output to the inverting input, and Rin is the resistor from the inverting input to ground. Unlike the inverting configuration, the output is in phase with the input.
Why is there always a +1 in the non-inverting gain formula?+
The +1 comes from the fact that at minimum (Rf = 0), the entire output voltage is fed back to the inverting input, forcing Vout to equal Vin exactly (a gain of 1). Adding a nonzero Rf reduces the feedback fraction, which increases the required gain above 1 to satisfy the feedback condition.
What is a voltage follower (buffer)?+
A voltage follower is the special case of a non-inverting amplifier with Rf = 0 (the output connected directly to the inverting input), giving a gain of exactly 1. It is used to buffer a signal, providing high input impedance and low output impedance without changing the signal's amplitude.
What is the input impedance of a non-inverting amplifier?+
The input impedance at the non-inverting input is essentially the op-amp's own input impedance (often megohms to gigohms), since no current from the source flows into Rin or Rf, this is why the non-inverting configuration is preferred when interfacing with high-impedance sources like sensors.
Can the non-inverting gain be less than 1?+
No, the non-inverting gain Av = 1 + Rf/Rin is always 1 or greater, since Rf and Rin are both non-negative resistances. To attenuate a signal (gain less than 1), use an inverting amplifier configuration or a passive voltage divider instead.
Does Rin draw current from the input signal?+
No, Rin connects between the inverting input and ground, not between the source and the inverting input, so it carries feedback current, not signal source current. This is why the non-inverting amplifier's input impedance is set by the op-amp itself, not by Rin.
How do I choose resistor values for a target gain?+
Pick any Rin in a practical range (commonly 1 to 10 kilohms), then solve Rf = Rin x (Av - 1) for the feedback resistor needed to hit your target gain. Many equally valid Rf/Rin pairs give the same gain, choose based on noise and power tradeoffs.
What limits the maximum output voltage?+
The op-amp's output voltage swing is limited by its supply rails, typically to within 1 to 2 volts of the positive and negative supply for standard op-amps, or much closer to the rails for rail-to-rail output parts. Vout calculated here assumes no clipping against those limits.
How is this different from the inverting configuration?+
The non-inverting amplifier keeps the output in phase with the input and always has gain of 1 or more with very high input impedance, while the inverting amplifier produces a 180-degree phase-inverted output, can have gain below 1, and has input impedance equal to its input resistor.
What units does this calculator use?+
Input and output voltages are in volts, and both resistors are in ohms. Gain Av is dimensionless (a ratio).
Tags: Non Inverting Op Amp Calculator Op-Amp Gain Calculator Voltage Follower Calculator Op Amp Buffer Calculator Operational Amplifier Calculator Calculator Formula Free Online

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What is the formula for non-inverting op-amp gain?

The closed-loop gain of a non-inverting amplifier is Av = 1 + Rf/Rin, where Rf is the feedback resistor from output to the inverting input, and Rin is the resistor from the inverting input to ground. Unlike the inverting configuration, the output is in phase with the input.

Why is there always a +1 in the non-inverting gain formula?

The +1 comes from the fact that at minimum (Rf = 0), the entire output voltage is fed back to the inverting input, forcing Vout to equal Vin exactly (a gain of 1). Adding a nonzero Rf reduces the feedback fraction, which increases the required gain above 1 to satisfy the feedback condition.

What is a voltage follower (buffer)?

A voltage follower is the special case of a non-inverting amplifier with Rf = 0 (the output connected directly to the inverting input), giving a gain of exactly 1. It is used to buffer a signal, providing high input impedance and low output impedance without changing the signal's amplitude.

What is the input impedance of a non-inverting amplifier?

The input impedance at the non-inverting input is essentially the op-amp's own input impedance (often megohms to gigohms), since no current from the source flows into Rin or Rf, this is why the non-inverting configuration is preferred when interfacing with high-impedance sources like sensors.

Can the non-inverting gain be less than 1?

No, the non-inverting gain Av = 1 + Rf/Rin is always 1 or greater, since Rf and Rin are both non-negative resistances. To attenuate a signal (gain less than 1), use an inverting amplifier configuration or a passive voltage divider instead.

Does Rin draw current from the input signal?

No, Rin connects between the inverting input and ground, not between the source and the inverting input, so it carries feedback current, not signal source current. This is why the non-inverting amplifier's input impedance is set by the op-amp itself, not by Rin.

How do I choose resistor values for a target gain?

Pick any Rin in a practical range (commonly 1 to 10 kilohms), then solve Rf = Rin x (Av - 1) for the feedback resistor needed to hit your target gain. Many equally valid Rf/Rin pairs give the same gain, choose based on noise and power tradeoffs.

What limits the maximum output voltage?

The op-amp's output voltage swing is limited by its supply rails, typically to within 1 to 2 volts of the positive and negative supply for standard op-amps, or much closer to the rails for rail-to-rail output parts. Vout calculated here assumes no clipping against those limits.

How is this different from the inverting configuration?

The non-inverting amplifier keeps the output in phase with the input and always has gain of 1 or more with very high input impedance, while the inverting amplifier produces a 180-degree phase-inverted output, can have gain below 1, and has input impedance equal to its input resistor.

What units does this calculator use?

Input and output voltages are in volts, and both resistors are in ohms. Gain Av is dimensionless (a ratio).

📌 Quick Tips

💡The non-inverting gain is always at least 1, unlike the inverting configuration, it can never attenuate a signal, only pass it through unchanged (Rf = 0) or amplify it (Rf greater than 0).
💡Setting Rf to 0 turns this into a voltage follower (unity-gain buffer), commonly used to isolate a high-impedance source from a low-impedance load without changing the signal amplitude.
💡Input impedance at the non-inverting input is set by the op-amp's own input impedance, typically megohms for bipolar-input op-amps and far higher for FET or CMOS-input op-amps, not by Rin or Rf.
💡Rin (the resistor from the inverting input to ground) does not draw current from the signal source, it only sets the feedback ratio, so its value can be chosen freely based on noise and bias-current tradeoffs.
💡For a target gain, an infinite number of Rf/Rin resistor pairs work equally well mathematically, in practice pick values in the low kilohm to low-hundred-kilohm range to balance noise, bias current error, and power consumption.