dB attenuation calculator
An attenuation of 6 dB leaves about half the voltage and about a quarter of the power. Enter one figure in decibels from a pad, a cable table or a filter sheet and get both linear ratios, plus percentages. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Attenuation db
- 6
- Gain db
- -6
- Voltage ratio
- 0.5011872336
- Power ratio
- 0.2511886432
- Voltage percent
- 50.1187233627
Attenuation in decibels is the everyday language of RF pads, coaxial cable loss tables, and filter stopband specifications, yet link budgets, SPICE netlists, and measurement scripts almost always need the underlying linear voltage and power transmission ratios. This dB attenuation ratio calculator accepts a single attenuation figure in decibels and returns both ratios at once: the voltage ratio Vout over Vin as ten to the power of minus A over twenty, and the power ratio Pout over Pin as ten to the power of minus A over ten.
Why attenuation needs both voltage and power linear ratios
Datasheets for fixed attenuator pads, cable assemblies, and band-stop or low-pass filters almost always quote insertion loss or stopband attenuation in decibels. Engineers then need the linear factors that actually scale voltages in a circuit or powers in a link budget. The definitions are fixed by the relationship between amplitude and power: attenuation in decibels equals minus twenty times the common logarithm of the voltage ratio, and also equals minus ten times the common logarithm of the power ratio.
Inverting those identities gives Vout over Vin equals ten raised to minus A over twenty, and Pout over Pin equals ten raised to minus A over ten. Forgetting which decade factor applies is a classic error: treating a six-decibel pad as a factor of one half on voltage instead of power (or the reverse) doubles the mistake in every cascade. Percent fields mirror the ratios times one hundred for UI meters and spreadsheet columns that expect a transmission percentage rather than a unitless multiplier.
Where teams use a dB attenuation calculator and what it costs
RF and microwave engineers convert pad attenuation and cable loss into linear factors before cascading stages in a link budget or before setting source levels on a signal generator. Filter designers map stopband attenuation specifications into power and voltage transmission ratios when comparing measured S21 curves against a requirement mask. Hardware QA scripts batch-convert mixed dB loss columns from VNA exports into linear ratios for dashboards that plot transmission, not logarithmic loss.
Educators and support pages embed the same conversion so students and customers never apply the wrong decade factor by hand when checking a three-decibel or ten-decibel example. Use a general decibel ratio converter when you need a bidirectional single-family conversion, or a voltage-gain calculator when you start from Vin and Vout rather than from a stated attenuation in dB.
What you can do with it
Resistive pad and attenuator design
Convert a pad’s rated attenuation in dB into voltage and power transmission ratios for cascading stages and checking available power after the pad.
Cable and feedline loss budgets
Turn coax or feedline loss figures from dB into linear power and voltage factors before summing a multi-hop RF or IF chain.
Filter stopband and S21 checks
Map stopband attenuation requirements or measured insertion loss in dB to linear ratios for mask comparison and automated QA reports.
FAQ
Does 3 dB attenuation mean half power?
Exactly half power is 10·log10(2) ≈ 3.010 dB.
Why does 6 dB halve the voltage but quarter the power?
Because voltage and power use different factors. The voltage ratio is ten to the power of minus the attenuation over twenty, while the power ratio uses ten instead of twenty. Mixing them up is a classic error that doubles in every stage.
What happens if I enter a negative attenuation?
A negative value is a gain: the ratios come out above one, and the result also shows the gain in decibels, which is the attenuation with its sign flipped.
What does an attenuation of 0 dB mean?
No loss at all. Both the voltage ratio and the power ratio are exactly one, so the output equals the input. Any positive value is a loss and pushes both ratios below one.
Is there a limit to the attenuation I can enter?
Yes. Values beyond 300 dB in either direction are refused, because the power ratio would no longer be a finite number. Any finite value inside that range is accepted, decimals included.
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/db-attenuation \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"attenuation_db":6}'const res = await fetch("https://api.kit.forhosting.com/elec/db-attenuation", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"attenuation_db": 6
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/elec/db-attenuation",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"attenuation_db": 6
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/elec/db-attenuation", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"attenuation_db":6}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"attenuation_db":6}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/elec/db-attenuation", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"attenuation_db": 6
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "elec.db_attenuation",
"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.
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
Use the page free, or automate identical inputs at $0.002 per successful request from prepaid KIT balance.
Why attenuation needs both voltage and power linear ratios
This capability always returns both ratios from one attenuation_db field so you never choose the wrong family mid-calculation. Positive attenuation means loss (ratios less than one), zero means no loss (ratios equal one), and a negative value is mathematically a gain, which the response also exposes as gain_db equals the negation of attenuation.
Input contract, formulas, and how to read the response
Results use fixed rounding so caches and goldens stay byte-stable across runtimes. POST a JSON body with attenuation_db, a finite number for attenuation in decibels. Aliases attenuation, att_db, A_db, loss_db, and db are accepted for the same field so lab CSV headers map without a rewrite step. Missing, empty, non-numeric, or non-finite values fail with invalid_input naming the problem; magnitudes beyond three hundred decibels are rejected to avoid overflow into non-finite powers. On success the body echoes attenuation_db, sets gain_db to its negation, and returns voltage_ratio and power_ratio from the formulas Vout over Vin equals ten to the minus A over twenty and Pout over Pin equals ten to the minus A over ten, plus voltage_percent and power_percent for display. Example anchors: three decibels of attenuation is roughly half power (power_ratio near zero point five) with voltage_ratio near zero point seven zero seven; six decibels is a quarter power and about half voltage; twenty decibels is one hundredth power and one tenth voltage; forty decibels is one ten-thousandth power. The implementation is pure parse work with no network, no model tokens, and no locale-dependent constants—identical in the free browser tool and the billed API path.
Where teams use a dB attenuation calculator and what it costs
Because the core is pure analytic math, the interactive page runs free in the browser and the API bills only successful calls at $0.002 per item from prepaid KIT balance; invalid input is not charged. Prefer this endpoint when search intent is specifically attenuation to linear voltage and power ratios for pads, cables, or filter stopbands.
Technical questions
How do I convert attenuation in dB to a linear voltage ratio?
Send attenuation_db as a finite number. The API returns voltage_ratio = 10^(-A_dB/20), which is Vout/Vin for that attenuation (positive A means loss).
How is the power ratio related to the voltage ratio?
Power ratio = 10^(-A_dB/10). For a matched resistive network, power_ratio equals voltage_ratio squared; both fields are returned so you need not square by hand.
What if I enter a negative attenuation?
Negative attenuation is treated as gain: ratios greater than one, and gain_db is the positive negation of attenuation_db. Pads and cable loss use positive attenuation.
What does the dB attenuation ratio calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.