Mass attenuation coefficient converter
Move μ/ρ values between radiology tables and SI reports: 0.2 cm²/g is 0.02 m²/kg. Nine area-per-mass units, including mm²/g and ft²/lb, for X-ray attenuation tables, CT protocol notes and shielding workbooks. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Value
- 0.2
- From
- cm2/g
- To
- m2/kg
- Result
- 0.02
- From label
- square centimeters per gram
- To label
- square meters per kilogram
- Base m2 kg
- 0.02
A mass attenuation coefficient converter turns a μ/ρ value written in one unit into another without hunting NIST footnotes or rewriting spreadsheet factors by hand.
Supported units and how the conversion is computed
The converter accepts mass attenuation coefficient μ/ρ under stable canonical codes that medical physicists, radiographers, shielding designers, and nuclear engineers use every day. The classic radiology table unit is cm2/g for square centimeters per gram; the coherent SI form is m2/kg for square meters per kilogram. Additional area-per-mass forms cover m2/g and cm2/kg, millimeter variants mm2/g and mm2/kg, milligram-denominator forms m2/mg and cm2/mg, and the US customary ft2/lb for square feet per pound.
One square centimeter per gram is exactly one tenth of a square meter per kilogram because one centimeter squared is ten to the minus four square meters and one gram is one thousandth of a kilogram. One square meter per gram is one thousand square meters per kilogram. One square millimeter per gram is one thousandth of a square meter per kilogram.
The international foot is exactly zero point three zero four eight meters and the avoirdupois pound is exactly zero point four five three five nine two three seven kilograms, so ft2/lb maps to m2/kg through the ratio of those exact identities. Because the intermediate is always m2/kg, converting A to B and B to A is consistent up to the published rounding of twelve decimal places, and there is no pairwise matrix that can drift out of sync when a new unit is added later.
Where μ/ρ conversions come up
Use the free in-browser mass attenuation coefficient converter when you need a quick centimeters-per-gram to meters-per-kilogram, millimeters-per-gram to centimeters-per-kilogram, or feet-per-pound to SI check while reading an X-ray attenuation table, a CT protocol note, a shielding workbook, a Monte Carlo material card, or a textbook appendix that mixes unit systems. 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 physicists and regulators expect on paper.
What you can do with it
NIST-style X-ray tables
Normalize published μ/ρ from cm²/g into m²/kg for SI reports and cross-code material cards without hand factors.
Shielding and dosimetry worksheets
Convert mixed radiology and SI mass-attenuation units when workbooks, vendor data, and lab sheets disagree.
Teaching and exam generators
Give students a deterministic cm²/g ↔ m²/kg oracle for homework checks and LMS auto-grading.
FAQ
Which mass attenuation units does this converter support?
cm2/g, m2/kg, m2/g, cm2/kg, mm2/g, mm2/kg, m2/mg, cm2/mg, and ft2/lb.
How do you convert square centimeters per gram to square meters per kilogram?
The engine multiplies by the exact m²/kg factor for the source (0.1) and divides by the m2/kg factor (1). Example: 0.2 cm2/g becomes 0.02 m2/kg.
What is the exact relationship between cm²/g and m²/kg?
All other supported pairs use the same SI identities (and exact foot/pound for ft2/lb).
What happens if I send an unknown unit?
The message names the field and lists supported units. Validation failures are not charged.
Is the mass attenuation coefficient converter free?
The browser tool runs free on your device.
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/mass-attenuation \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":0.2,"from":"cm2/g","to":"m2/kg"}'const res = await fetch("https://api.kit.forhosting.com/conv/mass-attenuation", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 0.2,
"from": "cm2/g",
"to": "m2/kg"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/mass-attenuation",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 0.2,
"from": "cm2/g",
"to": "m2/kg"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/mass-attenuation", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":0.2,"from":"cm2/g","to":"m2/kg"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":0.2,"from":"cm2/g","to":"m2/kg"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/mass-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
{
"value": 0.2,
"from": "cm2/g",
"to": "m2/kg"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.mass_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
The browser tool runs free on your device; the prepaid API charges $0.002 per successful item when pipelines need the same contract from servers and automation.
Supported units and how the conversion is computed
Friendly aliases such as square centimeters per gram, square meters per kilogram, cm²/g, m²/kg, cm^2/g, sq cm/g, and square feet per pound are normalized case-insensitively so forms and APIs can pass either short codes or full names. Every request multiplies the input by the exact square-meters-per-kilogram factor for the source, 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. Zero converts cleanly to zero in every target unit. Send a JSON body with three required fields: value as a finite non-negative number, from as the source unit string, and to as the target unit string. Aliases amount, quantity, and mu_rho 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 base_m2_kg quantity in square meters per kilogram, a dimensionless conversion_factor equal to the ratio of the two unit factors, a short formula line suitable for UI display, the method tag mass_attenuation_si, and the fixed list of units_supported. Missing value, non-finite numbers such as NaN or Infinity, negative values, 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. Extreme magnitude pairs remain well-defined as long as IEEE double precision can represent the intermediate product; typical μ/ρ values from soft tissue through lead at diagnostic and therapy energies sit comfortably inside that range.
Browser use, API pricing, and everyday workflows
Switch to the prepaid API when a radiology LIMS, radiation-protection report generator, materials database pipeline, educational quiz engine, or nuclear software plugin must convert μ/ρ 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 linear attenuation or density tools when a product pipeline needs those companions as well, or call it alone when search traffic is specifically for mass attenuation coefficient conversion—cm2/g, m2/kg, and μ/ρ—rather than a general unit switchboard.