Non-Inverting Op-Amp Gain Calculator
This Non-Inverting Op-Amp Gain Calculator finds the ideal closed-loop voltage gain set by the feedback resistor and ground resistor in a non-inverting amplifier.
Use it for first-pass analog gain planning, signal conditioning, sensor interface circuits, and lab checks where the ideal op-amp feedback equation is appropriate.
Engineering tool
Non-Inverting Op-Amp Gain Calculator
Calculate ideal closed-loop gain for a non-inverting op-amp amplifier from the feedback resistor and ground resistor.
Resistor from op-amp output to the inverting input.
Resistor from the inverting input to ground or reference.
Closed-loop gain (Av)
10 V/V
Result console
- Closed-loop gain
- 10V/V
- Gain
- 20dB
- Feedback ratio
- 9Rf/Rg
- Feedback resistor (Rf)
- 9kΩ
- Ground resistor (Rg)
- 1kΩ
Gain is valid for the ideal non-inverting op-amp model.
Formula reference
Non-Inverting Op-Amp Gain Formula
The ideal non-inverting amplifier assumes negative feedback, very high input impedance, zero input offset, no output swing limit, and enough op-amp bandwidth for the selected closed-loop gain.
Av = 1 + (Rf / Rg)Gain(dB) = 20 × log10(Av)Variable definitions
- Av
- Closed-loop voltage gain in V/V
- Rf
- Feedback resistor from output to the inverting input
- Rg
- Ground resistor from the inverting input to ground or reference
- Gain(dB)
- Voltage gain expressed in decibels
Variable Description
- Feedback resistor (Rf)
- The resistor connected between the op-amp output and the inverting input. Increasing Rf increases closed-loop gain.
- Ground resistor (Rg)
- The resistor connected between the inverting input and ground or a reference node. Rg must be greater than zero.
- Closed-loop gain (Av)
- The ideal non-inverting voltage gain ratio from input voltage to output voltage.
- Gain in dB
- The logarithmic voltage gain representation calculated from 20 × log10(Av).
Worked Examples
Example 1: Gain of 10
- Rf
- 9 kΩ
- Rg
- 1 kΩ
Av = 1 + (Rf / Rg)
Av = 1 + (9 kΩ / 1 kΩ) = 10
Gain = 10 V/V ≈ 20 dB
A gain of 10 multiplies the input voltage by ten in the ideal model, if output swing and bandwidth are sufficient.
Example 2: Gain of 100
- Rf
- 99 kΩ
- Rg
- 1 kΩ
Av = 1 + (Rf / Rg)
Av = 1 + (99 kΩ / 1 kΩ) = 100
Gain = 100 V/V ≈ 40 dB
A gain of 100 is useful in low-level signal conditioning, but real op-amp bandwidth, offset, noise, and output range must be checked.
Ideal op-amp assumption
The equation assumes infinite open-loop gain, zero input current, zero offset, unlimited output swing, and stable negative feedback.
Feedback network
Rf and Rg set the closed-loop gain ratio. Resistor tolerance, bias current, leakage, and noise affect real circuit accuracy.
Closed-loop gain
The non-inverting configuration preserves input polarity and has a minimum ideal gain of one when Rf is zero.
Input impedance
The signal source drives the non-inverting input, so input impedance is usually much higher than in an inverting amplifier.
Bandwidth tradeoff
Higher closed-loop gain reduces available bandwidth for a fixed gain bandwidth product.
Common Mistakes
Confusing inverting and non-inverting formulas
The non-inverting formula is Av = 1 + Rf/Rg. The inverting amplifier uses a different sign and resistor relationship.
Swapping Rf and Rg
Reversing the resistor positions changes the ratio and can produce a very different gain.
Ignoring units
Convert Ω, kΩ, and MΩ consistently before comparing resistor values.
Confusing gain and dB
A gain of 10 V/V is approximately 20 dB, while a gain of 100 V/V is approximately 40 dB.
Support reference
FAQ
What is a non-inverting amplifier?
A non-inverting amplifier is an op-amp circuit where the input signal is applied to the non-inverting input, so the output keeps the same polarity as the input while being amplified by the feedback network.
Why is the gain always greater than or equal to one?
The ideal non-inverting gain is Av = 1 + Rf/Rg. Since Rf cannot be negative and Rg must be greater than zero, the minimum ideal gain is one when Rf is zero.
How is gain in dB calculated?
Voltage gain in decibels is calculated with Gain(dB) = 20 × log10(Av), where Av is the voltage gain ratio in V/V.
What happens if Rf is zero?
If Rf is zero, the ideal non-inverting amplifier becomes a unity-gain buffer with Av = 1, or 0 dB voltage gain.
Why can't Rg be zero?
Rg appears in the denominator of Rf/Rg. A zero-ohm Rg would create division by zero and does not represent a valid ideal non-inverting gain equation.
Does this calculator include real op-amp bandwidth limits?
No. It calculates ideal closed-loop gain from resistor values. Real op-amps also require checks for gain bandwidth product, slew rate, output swing, input range, offset, and stability.
Related Engineering Guides
Dedicated op-amp guides are planned for this topic cluster. These guide topics are reserved for future publication and are shown without links until the pages exist.
Planned Engineering Guide
Operational Amplifier Basics
Planned guide covering ideal op-amp behavior, inputs, feedback, and common amplifier configurations.
Planned Engineering Guide
Choosing Feedback Resistors
Planned guide explaining feedback resistor ratios, tolerance, noise, input bias current, and practical value selection.
Planned Engineering Guide
Understanding Closed-Loop Gain
Planned guide covering gain, dB conversion, feedback factor, bandwidth tradeoff, and ideal versus real op-amp limits.
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Engineering Disclaimer
This calculator uses the ideal non-inverting op-amp gain equation. Verify resistor tolerance, op-amp gain bandwidth product, slew rate, input common-mode range, output swing, offset voltage, noise, supply rails, and stability before using the design in production hardware.