What is the gain formula for a non-inverting amplifier?

The closed-loop voltage gain is Gain = 1 + (Rf / R1). Because the input is applied to the non-inverting (+) terminal, the output is in phase with the input and the gain is always greater than or equal to 1. Setting Rf = 0 (or R1 = infinity) gives unity gain, which is the voltage-follower configuration.

How does a non-inverting amplifier differ from an inverting amplifier?

In a non-inverting amplifier the signal is fed to the + terminal, so the output is in phase with the input (no 180-degree inversion) and gain >= 1. In an inverting amplifier the signal enters at the - terminal through Rin, producing a sign-inverted output with gain = -(Rf/Rin). The non-inverting topology also presents a very high input impedance to the source.

What happens when Rf equals R1?

When Rf = R1 the closed-loop gain is exactly 2. The output is double the input voltage with no phase inversion. This is a common fixed-gain stage used in audio and instrumentation designs.

Does the op-amp supply voltage affect the calculation?

The formula Vout = (1 + Rf/R1) x Vin assumes an ideal op-amp with unlimited output swing. In practice the output saturates a volt or two below the positive rail. If your computed Vout exceeds the available headroom, the op-amp will clip.

Can I use this calculator for AC signals?

Yes. The gain formula gives the ideal mid-band result for any frequency where the op-amp open-loop gain is much larger than the closed-loop gain. At higher frequencies the gain-bandwidth product of the specific op-amp limits performance.

How do I design a voltage follower (unity gain buffer)?

Connect the output directly to the inverting (-) terminal with no resistors (Rf = 0, R1 = open). The gain is exactly 1. Voltage followers are used to buffer high-impedance sources, preventing them from being loaded by downstream circuitry.

Non-Inverting Amplifier Calculator

Name: Non-Inverting Amplifier Calculator
Availability: InStock
Author: Nham Vu

Enter the input voltage, R1, and Rf to instantly calculate the closed-loop gain and output voltage of an op-amp non-inverting amplifier.

Op-Amp Non-Inverting Amplifier

Calculation Mode

Input Voltage — V_in

Ground Resistor — R₁

Feedback Resistor — R_f

Enter values on the left and click Calculate to see results.

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Summary

Enter the input voltage, R1, and Rf to instantly calculate the closed-loop gain and output voltage of an op-amp non-inverting amplifier.

How it works

Select the calculation mode: compute gain from resistors, or find Rf for a target gain.
Enter the input voltage (Vin) in volts.
Enter the R1 (ground resistor) value in ohms, kilohms, or megaohms.
Enter the feedback resistor Rf (or target gain in solve mode).
The calculator applies Gain = 1 + (Rf / R1) to find the closed-loop gain.
Output voltage is computed as Vout = Gain x Vin, and results update instantly.

Use cases

Design buffer and amplifier stages that preserve signal polarity.
Size Rf and R1 for a specific gain target in a sensor interface circuit.
Verify resistor selections for audio preamplifier stages.
Quickly check gain and output swing before building a prototype.
Teach op-amp non-inverting amplifier theory with live feedback.
Convert low-level sensor outputs to ADC input ranges without phase inversion.
Design voltage followers by setting Rf to 0 and R1 to infinity (unity gain).
Estimate output voltage headroom against supply rails.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu