Ounces to grams converter
Turn the ounces on a US package or portion card into grams: 1 ounce is exactly 28.349523125 g and 16 ounces are 453.59237 g, so labels and lab records match standard tables instead of a times-28 guess. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Ounces
- 1
- Result
- 28.349523125 g
- Converted
- 28.349523125
- Grams
- 28.349523125
- From unit
- oz
An ounces-to-grams converter turns an avoirdupois ounce mass into the SI gram value used on product labels, lab notebooks, shipping docs, and metric recipes. Approximate mental shortcuts such as multiply by twenty-eight are rejected in favour of the hard-coded constant, so clinic records, package checks, and homework match engineering tables.
Why ounces and grams still meet at 28.349523125
Avoirdupois ounces remain the everyday mass unit on many US product packages, portion cards, postal scales, and body-composition tools that still quote smaller masses in ounces rather than pounds alone. Grams belong to the SI mass family used on scientific reports, most European and Asian labels, metric kitchen scales, and international shipping manifests. The bridge is exact by international agreement, not a survey approximation.
Since the nineteen fifty-nine international yard and pound agreement, one international avoirdupois pound is defined as exactly zero point four five three five nine two three seven kilograms, and that pound divides into exactly sixteen avoirdupois ounces. Dividing four hundred fifty-three point five nine two three seven grams by sixteen yields twenty-eight point three four nine five two three one two five grams per ounce. That makes the conversion a single exact multiplication: grams equals ounces times twenty-eight point three four nine five two three one two five.
Rough rules of thumb such as multiply by twenty-eight introduce scale error that shows up on multi-ounce packages or lab aliquots.
Practical tips, checks, and related searches
Prefer sending bare numbers when you control the client; string numbers are accepted only when they match a strict finite numeric pattern without units, thousand separators, or currency symbols. Round-trip sanity checks are easy: convert one ounce and confirm you receive exactly twenty-eight point three four nine five two three one two five grams after rounding, or convert sixteen ounces and confirm four hundred fifty-three point five nine two three seven grams—one international pound in grams.
When teaching, pair the exact path with a rough mental shortcut so students see the drift on larger masses. Stay inside the absolute range so the multiplication cannot overflow into a non-finite result the solver must reject.
This landing targets people searching for ounces to grams, convert oz to g, or an exact twenty-eight point three four nine five two three one two five calculator; it is not a general multi-unit mass hub, not a grams-to-ounces primary form, not a troy or fluid-ounce path, and not a cooking-only bidirectional kitchen converter. Prefer this capability when the input is already in avoirdupois ounces and you only need grams; if you need kitchen-scoped bidirectional oz and g with recipe framing, use the cooking ounces converter instead.
What you can do with it
Product labels and dual-unit packaging
Turn ounce package masses into grams for international labels, customs worksheets, and dual-unit product cards with the same exact factor every row.
Lab aliquots and portion tracking
Convert ounce scale readings to grams for lab notebooks, nutrition logs, and portion tools without rough times-twenty-eight estimates.
FAQ
Is 28.349523125 exact or approximate?
Exact by international definition. This tool uses the avoirdupois ounce from the 1959 pound, not a rough multiply-by-28 estimate.
Can I convert grams back to ounces?
This capability is ounces → grams only. Divide grams by 28.349523125 on your side, or use a bidirectional mass converter for other units.
Is the ounces to grams converter free?
The browser tool is free and runs locally.
How many grams is 16 ounces?
16 ounces are 453.59237 grams, exactly one international pound. Each ounce adds 28.349523125 grams, and the converter multiplies your ounces by that figure.
What goes wrong if I just multiply by 28?
Dropping the decimals of 28.349523125 loses a little on every ounce, and the gap becomes visible on multi-ounce packages or lab aliquots. The exact factor keeps clinic records and package checks in line with standard tables.
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/ounces-to-grams \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"ounces":1}'const res = await fetch("https://api.kit.forhosting.com/conv/ounces-to-grams", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"ounces": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/ounces-to-grams",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"ounces": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/ounces-to-grams", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"ounces":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"ounces":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/ounces-to-grams", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"ounces": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.ounces_to_grams",
"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
Invalid or missing input fails with a clear invalid_input error instead of inventing a number.
How to call the API and what comes back
Absolute values must stay within the published limit of one trillion. Send a JSON body with one required finite number field named ounces. Aliases oz, ounce, value, mass, weight, and oz_value are accepted so SDK clients and form posts can use the name that fits the product. On success the response echoes rounded ounces, sets grams, result, and converted to the same rounded gram magnitude, unit to the token g, from_unit to oz and to_unit to g, factor and g_per_oz to twenty-eight point three four nine five two three one two five, formula to the string grams equals ounces times twenty-eight point three four nine five two three one two five, message to a short English summary, and steps to an ordered array of substitution lines that show the avoirdupois ounce definition derived from the nineteen fifty-nine pound. Failed validation—missing fields, non-finite numbers, bare plus or minus signs, non-numeric strings, values outside absolute limits, or a non-finite converted result—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, checks, and related searches
Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately omit ounces or pass text.
Integration use cases
Homework and unit-test fixtures
Students and engineers convert classroom ounce masses to grams and pin golden JSON so browser and API arithmetic never drift.
Technical questions
What formula converts ounces to grams?
Grams = ounces × 28.349523125. One international avoirdupois ounce is exactly 28.349523125 g (from 1 lb = 0.45359237 kg and 16 oz per lb).
What happens on missing or non-numeric input?
The API returns invalid_input naming the problem (for example a missing ounces field). Failed tasks are not charged.