Speaker crossover calculator
A 1 mH inductor with a 10 µF capacitor sets a crossover corner close to 1592 Hz. Enter the inductance in henries and the capacitance in farads to see where a passive speaker crossover splits woofer and tweeter. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Inductance L in henries
- 0.001
- Capacitance C in farads
- 0.00001
- Crossover frequency hz
- 1,591.549430919 Hz
- Angular frequency rad s
- 10,000
- Precision
- 10
This speaker crossover calculator returns the corner frequency of a passive LC filter network from the inductor and capacitor you plan to install in a loudspeaker crossover. Enter inductance L in henries and capacitance C in farads, and the engine returns the crossover frequency fc in hertz together with the angular frequency ωc in radians per second, using the closed form fc equals one over two pi times the square root of L times C. That identity is the classic second-order LC target used when you already have parts on the bench and need the frequency they define before measuring the full acoustic response. Checks you can verify by hand include one millihenry with ten microfarads near fifteen hundred ninety-two hertz, and half a millihenry with four point seven microfarads near three thousand two hundred eighty-five hertz. The path is pure finite arithmetic with no network calls, no sampling, and no date-dependent shortcuts.
Where passive crossover frequency checks fit in design, repair, and software
Hobbyists and technicians meet the LC crossover formula when a parts list already specifies L and C and they want the electrical corner before measuring the assembled network, when salvaging a board and reading inductor and capacitor markings, or when verifying that a published crossover schematic lands near a known driver split. Teachers can pre-generate answer keys for modest L and C values without trusting opaque calculator apps that mix microfarads with farads or drop the two-pi factor.
Developers call the same contract from scripts to seed deterministic test vectors for audio design tools, to normalize user-entered component pairs before optimization demos, or to satisfy programming-challenge statements that demand fc rather than a hand-waved estimate. Contest and repair practice often needs a fast, offline source of crossover frequency so solutions can be checked without a full acoustic measurement under time pressure.
Product and education tools use the formula when a learner types L and C and the UI must show the corner in hertz next to a simple schematic. Pair it with resonance, capacitor-energy, or inductor-energy helpers when you are building a small lab of free, deterministic electronics calculators for audio and power work.
What you can do with it
Bench parts to corner frequency
Read L and C from a passive crossover board or BOM and confirm the electrical split frequency before acoustic measurements.
Teaching and repair worksheets
Give students or technicians known L–C pairs and the expected crossover frequency without opaque calculator apps.
FAQ
What does the speaker crossover calculator cost?
It is free in your browser on this page.
What happens if L or C is zero?
Zero or negative inductance or capacitance makes the LC crossover formula undefined.
Does this size L and C for a target frequency and speaker impedance?
No. It only returns the frequency implied by a given L and C pair. Sizing components from fc and load R is a separate design step.
Can I enter millihenries and microfarads directly?
No. Convert them first: 1 millihenry is 0.001 henry and 10 microfarads are 0.00001 farad. Mixing scales gives a frequency that looks plausible but is wrong, a frequent slip with this formula.
What is the angular frequency shown next to the result?
It is the same corner in radians per second, equal to two pi times the frequency in hertz. For 1 mH and 10 µF it is 10000 rad/s, while the frequency is close to 1592 Hz.
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/crossover-frequency \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"inductance":0.001,"capacitance":0.00001}'const res = await fetch("https://api.kit.forhosting.com/elec/crossover-frequency", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"inductance": 0.001,
"capacitance": 0.00001
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/elec/crossover-frequency",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"inductance": 0.001,
"capacitance": 0.00001
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/elec/crossover-frequency", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"inductance":0.001,"capacitance":0.00001}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"inductance":0.001,"capacitance":0.00001}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/elec/crossover-frequency", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"inductance": 0.001,
"capacitance": 0.00001
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "elec.crossover_frequency",
"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_l | 1000000000000000 |
max_abs_c | 1000000000000000 |
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
What the LC crossover frequency means and what the response contains
A passive speaker crossover steers low frequencies to the woofer and high frequencies to the tweeter using inductors and capacitors so each driver works in its safe band. For an ideal LC network the design corner is the frequency where the reactive magnitudes balance: fc equals one over two pi times the square root of L times C, with L in henries and C in farads yielding fc in hertz. The companion angular frequency is omega c equals one over the square root of L times C in radians per second, related by omega c equals two pi times fc. This calculator returns the normalized inductance and capacitance you supplied, the crossover frequency in hertz, the angular frequency in radians per second, the decimal precision used, a method tag lc_crossover_frequency, a short formula string, and a unit field set to hertz. There is no approximate SPICE path and no random sampling of component tolerances: the engine either builds exact floating-point fc and omega c inside the supported magnitude range or rejects the input with invalid_input. Rejected cases include missing inductance or capacitance, non-finite values, magnitudes above the documented ceiling, and any L or C that is zero or negative, because the square-root formula is undefined for non-positive products.
How inductance and capacitance are read and how results stay reproducible
Convert millihenries and microfarads to SI before calling: one millihenry is zero point zero zero one henries, and ten microfarads is zero point zero zero zero zero one farads. Optional leading plus signs and scientific notation on numeric strings are allowed when they parse as finite decimals; embedded spaces, hex prefixes, and non-numeric tokens are rejected with a clear message so a bad cell does not become a wrong corner frequency. The preferred fields are inductance for L in henries and capacitance for C in farads, but aliases L, l, henries, and henry for inductance, and C, c, farads, and farad for capacitance are accepted so spreadsheets, query strings, and typed forms can reuse the same contract. Zero or negative L or C is never accepted: if either value is at or below zero, the request fails with invalid_input because fc would be undefined or non-physical for a passive crossover. An optional precision field, with aliases decimals and dp, chooses how many decimal places to expose for inductance, capacitance, fc, and omega c, defaulting to ten and capped at fifteen so JSON goldens stay stable. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing the square-root formula yourself.
Where passive crossover frequency checks fit in design, repair, and software
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a bench demo to an automated pipeline without changing the mathematical result.
Integration use cases
Deterministic audio test fixtures
Generate reproducible fc and ωc values for unit tests, design-tool goldens, and CI assertions on LC networks.
Technical questions
How is the crossover frequency defined?
For inductance L in henries and capacitance C in farads, both positive, fc = 1/(2π√(LC)) in hertz and ωc = 1/√(LC) in rad/s.
Do I enter millihenries and microfarads directly?
No. Convert to SI first: 1 mH = 0.001 H and 10 µF = 0.00001 F. The calculator expects henries and farads.