Absorbed dose converter
1 gray is exactly 100 rad: the converter passes every dose through grays to move between Gy, mGy, rad and erg/g, so old rad charts, imaging reports and film-badge records can be compared side by side. 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
- Gy
- To
- Rad
- Result
- 100 rad
- Converted
- 100
- Value gy
- 1
- Factor
- 100
An absorbed radiation dose converter turns one energy-deposition magnitude into another unit without spreadsheet factors or mental powers of ten. Enter a finite value plus a source unit and a target unit among gray, milligray, rad, and erg per gram; the tool returns the converted dose, the SI intermediate in grays, the exact unit factor applied, and step-by-step substitution lines you can paste into a lab notebook, protocol, or report. Health-physics technicians comparing survey meter readings, radiation oncology staff reconciling historical rad charts with modern gray prescriptions, industrial radiographers converting film badge data, and students checking textbook energy-per-mass examples all need the same deterministic path.
Which absorbed-dose units are supported and how conversion works
This capability converts among four absorbed-dose units that dominate radiation protection, medical physics, industrial radiography, and teaching materials. The gray (Gy) is the SI coherent unit of absorbed dose—one joule of energy deposited per kilogram of matter—and the internal hub: every conversion multiplies the input by how many grays equal one source unit, then divides by how many grays equal one target unit. The milligray (mGy) is one thousandth of a gray and is common on diagnostic imaging dose reports and environmental survey instruments.
The rad is the older CGS-linked unit still present on historical charts, film-badge archives, and some regulatory tables; by exact definition one rad equals one hundredth of a gray, so one gray equals one hundred rad. Erg per gram is the energy-density form that underlies the classical definition of the rad: one rad equals one hundred erg per gram, which implies one erg per gram equals exactly one ten-thousandth of a gray and one gray equals ten thousand erg per gram.
English names such as gray, grays, milligray, rad, rads, erg per gram, and ergs per gram resolve to the same canonical symbols Gy, mGy, rad, and erg/g. Compact spellings with slashes or spaces for the erg unit are accepted after normalization. Same-unit requests succeed and return the input magnitude with a short message that no change of unit was required.
Practical tips, limits, and when to use this landing
Prefer sending bare numbers for value when you control the client; string numbers are accepted only when they match a strict finite numeric pattern without currency symbols or thousand separators. Round-trip checks are straightforward: convert A to B and B back to A and confirm you recover the original within the published twelve-decimal rounding.
Classic teaching pairs include one gray equals one hundred rad, one gray equals ten thousand erg per gram, one rad equals one hundred erg per gram, one milligray equals zero point one rad, and one hundred milligray equals ten rad. Stay inside the absolute range so intermediate gray values cannot overflow; for very large total-body or multi-fraction inventories choose a coarser target unit such as Gy instead of expanding everything to erg per gram.
This landing targets people searching for an absorbed dose converter, gray to rad, milligray to gray, rad to Gy, or erg per gram conversion online; it is not a radioactivity (becquerel or curie) converter, not an equivalent-dose or sievert calculator, not an exposure (roentgen) tool, and not a decay-chain solver.
What you can do with it
Historical rad charts to gray protocols
Radiation oncology and therapy planning systems receive legacy prescriptions in rad while modern protocols use Gy; staff convert absorbed dose once with exact factors before plan approval.
Survey meter and badge report units
Health-physics teams read instruments in mGy or rad and must report Gy or erg/g on certificates; analysts convert without spreadsheet factor drift.
Teaching energy-per-mass problems
Students and instructors convert textbook absorbed-dose examples among Gy, mGy, rad, and erg per gram with deterministic step strings for homework and lab notebooks.
FAQ
Which absorbed-dose units can I convert?
Gray (Gy), milligray (mGy), rad, and erg per gram (erg/g). English names such as gray, milligray, and erg per gram are accepted.
Is the absorbed dose converter free?
The browser tool is free and runs locally.
How many rad are in one gray?
One gray equals 100 rad. The rad is defined as one hundredth of a gray, so going from gray to rad multiplies by 100 and going back divides by 100, with no rounding.
Can I convert sieverts or rem here?
No. Only gray, milligray, rad and erg per gram are accepted. Names such as sievert, rem or becquerel are refused with a clear message instead of being converted with a wrong factor.
How does a milligray compare with a rad?
One milligray equals 0.1 rad. Diagnostic imaging reports and survey instruments often use mGy, while older charts and film-badge archives use rad, so this pair comes up often.
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/absorbed-dose \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":1,"from":"Gy","to":"rad"}'const res = await fetch("https://api.kit.forhosting.com/conv/absorbed-dose", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 1,
"from": "Gy",
"to": "rad"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/absorbed-dose",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 1,
"from": "Gy",
"to": "rad"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/absorbed-dose", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":1,"from":"Gy","to":"rad"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":1,"from":"Gy","to":"rad"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/absorbed-dose", 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": "Gy",
"to": "rad"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.absorbed_dose",
"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 | 1000000000000000000 |
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
Unknown unit names fail with a clear invalid_input error instead of silent wrong factors.
Which absorbed-dose units are supported and how conversion works
If the name is not on the supported list—for example sievert, rem, becquerel, or a free-text typo—the solver rejects the request with invalid_input naming the bad field and listing example units, so clients never guess whether a typo produced a wrong number. Absolute magnitude must stay within the published one-quintillion limit so intermediate products remain finite in IEEE double precision on the Worker and in the browser.
How to call the API and read the response
Value must be a finite number or a strict numeric string within absolute limits of one quintillion. Wire this into radiation information systems, oncology dose calculators, industrial NDT reporting pipelines, or batch jobs that already hold an absorbed-dose reading and only need a second unit for display, regulatory comparison, or archive migration without shipping floating conversion tables in every app binary. Send a JSON body with three required fields: value (aliases dose, amount, and n), from (aliases from_unit, unit_from, and source), and to (aliases to_unit, unit_to, and target). From and to must resolve to supported unit names after alias normalization. On success the response echoes the rounded input value, canonical from and to labels, result and converted set to the same rounded target magnitude, value_gy as the SI intermediate in grays, unit as the target label, factor as the from-to multiplier, formula as the short equation string, message as an English summary, steps as ordered substitution lines, and supported_units as the full list of canonical identifiers. Failed validation—missing fields, non-finite numbers, values outside absolute limits, or an unknown unit name—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 when to use this landing
Normalize display labels on your side if you need locale-specific spellings—this API always returns short canonical tokens such as Gy, mGy, rad, and erg/g so automated tests stay stable. Prefer this capability when both endpoints are among the four supported absorbed-dose units and you need deterministic factors and step strings; if you only need to reformat a number for a locale without changing physical unit, use a number-format capability instead. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when clients deliberately probe unknown unit names.
Technical questions
What happens if I send an unknown unit name?
The API returns invalid_input, names the bad field, and lists example supported units. The failed task is not charged.
How are rad and erg/g defined here?
One rad equals exactly 0.01 Gy. One erg/g equals exactly 1e-4 Gy (so 1 Gy = 100 rad = 10,000 erg/g, and 1 rad = 100 erg/g).
Are results deterministic across browser and API?
Yes. Handler and widget share the same lib.js solve path with fixed conversion factors and twelve-decimal rounding, so golden examples match production.