Current density converter
1 A/mm² is 1,000,000 A/m²: convert current density between nine units, from A/m², A/cm² and A/mm² to A/in², A/ft² and their milli or kilo variants, for cable sizing, plating lines and battery electrodes. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Value
- 1
- From
- A/mm2
- To
- A/m2
- Result
- 1,000,000
- From label
- ampere per square millimetre
- To label
- ampere per square metre
- A per m2
- 1,000,000
Electric current density measures how much current flows through a unit of cross-sectional area—the J vector that links ampacity, conductor sizing, plating lines, battery electrodes, and electromagnetics textbooks. Engineers and students often receive values in amperes per square millimetre from cable datasheets, amperes per square inch from North American design guides, milliamperes per square centimetre from electrochemistry labs, or amperes per square metre from SI homework, and need a trustworthy conversion without rebuilding area factors by hand.
Supported units and exact conversion factors
The converter accepts nine electric current density families under stable canonical codes: A/m2 for amperes per square metre (SI), A/cm2 and A/mm2 for ampere per square centimetre and millimetre, A/in2 and A/ft2 for ampere per square inch and foot, plus mA/m2, mA/cm2, kA/m2, and kA/cm2 for milli and kilo prefixes common in plating, fuse, and bus-bar work.
Area factors follow SI definitions: one square centimetre is exactly ten to the minus four square metres, one square millimetre is ten to the minus six, one square inch is exactly zero point zero two five four metres squared, and one square foot is zero point three zero four eight metres squared.
Prefix units scale current only: one milliampere per square metre is one thousandth of an ampere per square metre, one milliampere per square centimetre equals ten amperes per square metre, one kiloampere per square metre is one thousand amperes per square metre, and one kiloampere per square centimetre equals ten million amperes per square metre. Because the intermediate is always A/m², converting A to B and B to A is consistent up to the published twelve-decimal rounding, and there is no pairwise matrix that can drift out of sync.
Bare electric current without area, magnetic flux density, and charge density are intentionally out of scope so power and process users get predictable J-only results under one clear convention.
Where current density figures appear
Use the free in-browser current density converter when you need a quick A/mm² to A/in², A/m² to A/cm², or mA/cm² to A/m² check while reading a cable catalogue, electroplating specification, battery electrode note, fuse rating sheet, or electromagnetics homework problem. Open the page, enter the number and units, and copy the result without installing a spreadsheet, a unit library, or a desktop calculator pack. Source inputs follow the same retention rules as other KIT parse items, and results are safe to cache because the algorithm is fully deterministic.
Authors shipping mobile apps or chatbots can map the result and formula fields directly into cards that show both the number and the conversion path students, process engineers, and power designers expect on paper.
What you can do with it
Cable and bus-bar ampacity notes
Convert A/mm² catalogue limits into A/in² or A/m² for mixed SI and customary design reviews without hand-built factor tables.
Electroplating and battery electrodes
Map mA/cm² plating densities and lab electrode currents into A/m² SI reports with exact centimetre area factors and clear typos errors.
FAQ
How is A/in² related to A/m²?
One square inch is exactly (0.0254 m)². The converter multiplies by 1/(0.0254)² so 1 A/in2 equals about 1550.0031 A/m2 with stable twelve-decimal rounding.
What if I send an unknown unit?
The message names the bad field and lists supported units; validation failures are not charged.
Is the current density converter free?
The browser tool runs free on your device.
Does it convert electric current without area?
No. This capability only converts current density J (current per area). Bare amperes, milliamperes, or kiloamperes alone are out of scope.
Why is 1 mA/cm² equal to 10 A/m²?
Because two changes pull in opposite directions. Milli divides the current by 1,000, but a square centimetre is only a ten-thousandth of a square metre, so the density per square metre ends up 10 times larger.
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/conv/current-density \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":1,"from":"A/m2","to":"A/mm2"}'const res = await fetch("https://api.kit.forhosting.com/conv/current-density", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 1,
"from": "A/m2",
"to": "A/mm2"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/current-density",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 1,
"from": "A/m2",
"to": "A/mm2"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/current-density", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":1,"from":"A/m2","to":"A/mm2"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":1,"from":"A/m2","to":"A/mm2"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/current-density", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"value": 1,
"from": "A/m2",
"to": "A/mm2"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.current_density",
"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
This capability converts a numeric current density from one supported unit to another with fixed SI area definitions (inch exactly 0.0254 m, foot exactly 0.3048 m), routes every pair through A/m² as the intermediate base, and returns deterministic JSON for APIs, SDKs, and free browser use. Unknown unit names fail with a clear invalid_input error so forms and pipelines never silently invent a factor.
Supported units and exact conversion factors
Friendly aliases such as A/m², A/m^2, ampere per square millimeter, amps/mm2, and mA/cm² are normalized so forms can pass short codes or spelled names. Every request multiplies the input value by the exact amperes-per-square-metre factor for the source unit, then divides by the factor for the target.
Request shape, response fields, and unknown-unit errors
The error message names the bad field and lists the supported set so clients can correct forms without guessing. Negative values are allowed when you need signed current density for directed flow or alternating-cycle averages expressed with polarity; zero converts cleanly to zero in every target unit. Send a JSON body with three required fields: value as a finite number, from as the source unit string, and to as the target unit string. Aliases amount, quantity, and j are accepted for value; unit_from and source for from; unit_to and target for to. On success the response echoes the canonical from and to codes, human-readable from_label and to_label strings, the converted result, the intermediate a_per_m2 quantity in amperes per square metre, the dimensionless factor from source to target, a short formula line suitable for UI display, the method tag current_density_si, and the fixed list of units_supported. Missing value, non-finite numbers such as NaN or Infinity, missing unit fields, and any token that does not map to a supported unit fail with invalid_input and are not charged after the engine rejects the request. Identical inputs always yield identical JSON because the path is pure arithmetic with no randomness, no remote lookup, and no dependence on the wall clock, which makes the endpoint safe to pin in continuous-integration goldens and SDK contract tests. Milliampere-scale electrode results and kiloampere-per-square-metre bus-bar results share the same code path, so extreme magnitude pairs remain well-defined as long as IEEE double precision can represent the intermediate product.
Browser use, API pricing, and everyday workflows
Switch to the prepaid API when a cable sizing tool, plating line controller, battery design notebook, physics homework checker, or power-electronics CAD plugin must convert current density at scale under a stable KIT contract at $0.002 per successful item; validation failures that raise invalid_input do not consume balance after rejection. Pair this endpoint with electric current or resistance tools when a product pipeline needs several electrical measure families, or call it alone when search traffic is specifically for current density conversion—amperes per square metre, centimetre, millimetre, inch, and foot, plus milli and kilo prefixes—rather than a general unit switchboard.
Integration use cases
Power and homework automation
Normalize current density units in design pipelines and homework checkers via a prepaid, deterministic API instead of ad-hoc spreadsheet factors.
Technical questions
Which current density units are supported?
A/m2, A/cm2, A/mm2, A/in2, A/ft2, mA/m2, mA/cm2, kA/m2, and kA/cm2, plus common spelled aliases. Unknown names return invalid_input.