Non-inverting amplifier calculator
Rf of 10 kΩ over Rg of 1 kΩ gives a non-inverting op-amp a gain of 11, about 20.8 dB, with the signal polarity kept. Enter the two resistors to get the gain, the ratio and each substitution step for your lab report. Free in your browser.
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Run — free
Worked example
- Rf
- 10,000
- Rg
- 1,000
- Gain
- 11
- Voltage gain
- 11
- Av
- 11
- Ratio rf rg
- 10
A non-inverting amplifier calculator turns the two feedback resistors of an ideal op-amp into closed-loop voltage gain. Enter feedback resistor Rf between the output and the inverting input, and grounded resistor Rg from the inverting input to the signal reference; the tool returns Av equals one plus Rf over Rg, the intermediate ratio, gain in decibels, and step-by-step substitution you can paste into lab reports or homework. Non-inverting stages keep the signal polarity, present high input impedance at the non-inverting pin, and appear in sensor buffers, audio preamps, and ADC drivers whenever you need gain greater than or equal to one without inversion.
Why the gain never drops below one
In the classic non-inverting configuration an ideal operational amplifier drives its output so that the differential input voltage is zero under negative feedback. The input signal connects to the non-inverting pin while a resistive divider from the output to ground (or signal common) feeds a fraction of the output back to the inverting pin. That divider is Rf in series with Rg: Rf sits between output and inverting input, and Rg sits between inverting input and ground.
Virtual-ground analysis then shows that the voltage at the inverting node equals the input voltage, so Vin equals Vout times Rg over Rf plus Rg. Solving for the ratio Vout over Vin produces the closed-loop voltage gain Av equals one plus Rf over Rg. Unity gain appears when Rf is zero or shorted—the well-known voltage follower—while large Rf over Rg ratios produce high gain limited in practice by open-loop bandwidth and stability, not by this ideal formula.
Teachers and automated graders care about the zero-Rg rejection as much as the algebra: a student who sets Rg to zero has left the domain of a passive feedback divider, and a silent Infinity would hide that mistake. Near-zero floating values at or below one times ten to the minus fifteen are treated as zero and rejected the same way so noise does not invent a huge ratio term.
Keep both resistors in the same unit—ohms, kilohms, or megohms—because only their ratio enters the formula, not their absolute scale, as long as units match.
Practical tips, limits, and related searches
Keep both resistors in the same unit before you call: mixing ohms with kilohms without converting will produce a nonsense gain that looks numeric but is wrong by three orders of magnitude on the ratio. Prefer sending numbers rather than pre-formatted engineering strings when you control the client; string numbers are accepted only when they match a strict finite numeric pattern.
For hand checks, Rf equals ten kilohms and Rg equals one kilohm should return Av equals eleven and about twenty point eight decibels; Rf equals zero with any positive Rg should return Av equals one for a follower; equal Rf and Rg should return Av equals two. When teaching, pair the ideal formula with a reminder that real chips have finite open-loop gain, input bias current, and gain-bandwidth product, so this tool is the first design step, not the final SPICE check.
This landing targets people searching for a non-inverting amplifier calculator, op-amp gain one plus Rf over Rg, or non-inverting closed-loop gain online; it is not an inverting-amplifier solver, not a difference-amplifier tool, and not a full noise or stability analyzer. Prefer this capability when the topology is already non-inverting and you only need Av from two resistors; if your circuit is inverting, use an inverting gain tool instead.
What you can do with it
Sensor buffer and ADC front-end design
Engineers pick feedback and ground resistors to hit a target gain greater than or equal to one while keeping high input impedance on the non-inverting pin.
FAQ
What is the gain of a non-inverting op-amp?
The output has the same polarity as the input.
Does this model real op-amp limitations?
No. It returns ideal closed-loop gain only. Finite open-loop gain, bandwidth, offset, and stability require a full circuit simulator.
Is the non-inverting amplifier calculator free?
The browser tool is free and runs locally.
What happens if Rg is zero?
It is rejected with a clear message, because the feedback divider becomes undefined and an infinite gain would hide the mistake. Values that are practically zero are treated the same way, so numeric noise cannot invent a huge gain.
Can Rf be zero?
Yes. With Rf at zero or shorted, the gain is exactly 1, which is the familiar voltage follower. Only a negative value is refused, because it does not describe a passive network.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/elec/op-amp-noninverting \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"rf":10000,"rg":1000}'const res = await fetch("https://api.kit.forhosting.com/elec/op-amp-noninverting", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"rf": 10000,
"rg": 1000
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/elec/op-amp-noninverting",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"rf": 10000,
"rg": 1000
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/elec/op-amp-noninverting", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"rf":10000,"rg":1000}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"rf":10000,"rg":1000}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/elec/op-amp-noninverting", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"rf": 10000,
"rg": 1000
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "elec.op_amp_noninverting",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs | 1000000000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
When the grounded resistor is zero the divider is undefined, so the API returns a clear invalid_input error instead of inventing infinite gain.
How to call the API and what comes back
The grounded resistor rg must be strictly positive and non-zero; values whose absolute value is at or below one times ten to the minus fifteen are treated as zero and rejected, and negatives are rejected as non-physical for a passive network. Feedback resistor rf may be zero for a unity-gain buffer but must not be negative. Send a JSON body with two required finite numbers: rf (aliases Rf, R_f, feedback, feedback_r) and rg (aliases Rg, R_g, ground, ground_r, r_g). Absolute values must stay within the published limit of one trillion so intermediate ratios remain finite in IEEE double precision on the Worker and in the browser. On success the response echoes rounded rf and rg, sets gain, voltage_gain, and av to the same rounded Av equals one plus Rf over Rg, ratio_rf_rg to Rf over Rg, gain_db to twenty times log base ten of Av, formula to the string Av equals one plus Rf over Rg, configuration to non_inverting, message to a short English summary, and steps to an ordered array of substitution lines. Failed validation—missing fields, non-finite numbers, zero or near-zero rg, negatives, values outside absolute limits, or a non-finite gain—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.
Practical tips, limits, and related searches
Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately type a zero ground resistor. Round-trip checks are easy: recompute one plus Rf over Rg by hand and confirm it equals the published gain within the same twelve-decimal rounding, and confirm that twenty log ten of that gain matches gain_db.
Integration use cases
Homework checks for non-inverting gain
Students enter Rf and Rg from textbook schematics and compare hand-written Av and dB against a deterministic browser or API result before submitting.
Unit tests for education apps and firmware
Generate known-good Av values, unity-gain follower cases, and deliberate zero-Rg rejections for coding kata expected JSON or embedded calculator fixtures.
Technical questions
What happens when the grounded resistor Rg is zero?
The feedback divider is undefined. This tool returns invalid_input instead of reporting infinite gain.
Can Rf be zero?
Yes. Rf = 0 with positive Rg gives Av = 1, the classic voltage follower or unity-gain buffer.