Non-Inverting Op-Amp Gain Calculator
A non-inverting amplifier is one of the building-block configurations of the operational amplifier, used wherever a signal needs to be boosted without flipping its polarity. Its voltage gain is set entirely by two resistors in the feedback network and is wonderfully simple: one plus the ratio of the feedback resistor to the input resistor. Because of the leading one, the gain is always at least unity, so a non-inverting stage can amplify but never attenuate below the input level, and a voltage follower is just the special case where the feedback resistor is zero. This calculator takes the feedback resistor and the input (ground-side) resistor, in any consistent resistance unit, and returns the closed-loop voltage gain to two decimal places along with the equivalent gain in decibels. The formula assumes an ideal op-amp with high open-loop gain and negligible input current. Raising the feedback resistor or lowering the input resistor increases the gain. The definitions of the ohm and the other electrical units are maintained by the National Institute of Standards and Technology. Every figure here is computed deterministically from the gain formula, shown below, with a worked example that reconciles exactly to the calculator so you can check each step yourself.
The non-inverting gain is 1 + Rf / Rin. With a feedback resistor of 10,000 ohms and an input resistor of 1,000 ohms, the gain is 11.00x (about 20.83 dB). A non-inverting stage never has gain below one.
Non-inverting op-amp gain formula
Gain = 1 + Rf / Rin
Gain = closed-loop voltage gain (V/V)
Rf = feedback resistor (ohms)
Rin = input/ground-side resistor (ohms)
Divide the feedback resistor by the input resistor and add one. The leading one means a non-inverting amplifier always has a gain of at least unity. Setting Rf to zero (or Rin to infinity) gives a gain of exactly one, a unity-gain buffer.
Worked example
A non-inverting amplifier uses a feedback resistor Rf of 10,000 ohms and an input resistor Rin of 1,000 ohms.
- Divide Rf by Rin: 10,000 / 1,000 = 10
- Add one: 1 + 10 = 11
- The voltage gain is 11.00x
- In decibels: 20 x log10(11) = 20.83 dB
So the amplifier multiplies the input voltage by 11.00 (about 20.83 dB). These are the calculator's default inputs, so the result above matches the widget exactly.
Non-Inverting Op-Amp Gain Calculator: frequently asked questions
How do you calculate non-inverting op-amp gain?
The closed-loop voltage gain is 1 + Rf / Rin, where Rf is the feedback resistor and Rin the input resistor to ground. With Rf = 10,000 ohms and Rin = 1,000 ohms, the gain is 1 + 10 = 11. The output stays in phase with the input.
Why is there a plus one in the formula?
The input signal is applied directly to the non-inverting terminal, so it appears at the output even with no feedback resistor, contributing a gain of one. The feedback ratio Rf / Rin adds amplification on top, giving 1 + Rf / Rin.
Can a non-inverting amplifier have a gain below one?
No. Because of the leading one, the gain is always at least unity. To attenuate a signal you need a different configuration, such as a resistive divider or an inverting amplifier with Rf smaller than Rin.
What is a unity-gain buffer?
It is a non-inverting amplifier with a gain of exactly one, achieved by making the feedback resistor zero (a direct connection) and omitting the input resistor. It provides isolation and a low output impedance without changing the signal level.
What is the non-inverting gain formula?
The voltage gain of a non-inverting op-amp is 1 + Rf / Rin.
Official sources
- Electrical units and measurement standards: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.