KG to stone converter
Turn a weight in kilograms into British stone with the exact factor: 6.35029318 kg make 1 stone, and 70 kg come to just over 11 stone. Made for UK health charts, boxing weigh-ins and everyday talk. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Kg
- 6.35029318
- Result
- 1 st
- Converted
- 1
- Stone
- 1
- From unit
- kg
A kilograms-to-stone converter turns a metric body weight or cargo mass into the British stone value still used on UK health charts, sports weigh-ins, and everyday conversation. Approximate mental shortcuts such as multiply by zero point one five seven are rejected in favour of the composed international constants, so clinic records and homework checks match engineering tables.
Why kilograms and stone still meet at 6.35029318
Kilograms belong to the SI mass family used on bathroom scales outside imperial settings, scientific reports, shipping manifests, and most European product labels. Stone remains a familiar unit for human body weight in the United Kingdom and Ireland: people still say they weigh eleven stone rather than seventy kilograms, and many UK sports, boxing, and medical conversations quote mass that way. The bridge is exact by composition, not a survey approximation.
One stone is defined as fourteen avoirdupois pounds, and since the 1959 international yard and pound agreement one international pound is exactly zero point four five three five nine two three seven kilograms. Multiplying those constants yields six point three five zero two nine three one eight kilograms per stone with no leftover uncertainty. That makes the conversion a single exact division: stone equals kilograms divided by six point three five zero two nine three one eight, or equivalently kilograms times the reciprocal factor.
Rough rules of thumb such as multiply by zero point one five seven introduce scale error that shows up on a seventy-kilogram body weight or a multi-hundred-kilogram load.
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 the textbook value six point three five zero two nine three one eight kilograms and confirm you receive exactly one stone after rounding, or convert seventy kilograms and confirm roughly eleven point zero two three one one three one zero nine two four stone.
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 division cannot overflow into a non-finite result the solver must reject. This landing targets people searching for kg to stone, convert kilograms to stone, or an exact six point three five zero two nine three one eight calculator; it is not a general multi-unit mass hub, not a stone-to-kilograms primary form, not a stone-and-pounds split display, and not a pounds-only converter.
Prefer this capability when the input is already in kilograms and you only need stone; if you must convert among many mass units in one call, use a broader unit converter instead.
What you can do with it
UK body-weight and health charts
Turn metric clinic or scale readings into stone for UK-facing patient notes, sports weigh-ins, and wellness dashboards with the same exact factor every row.
Sports and boxing weigh-ins
Coaches convert kilogram weigh-in results to stone for UK categories and compare hand work against deterministic steps before publishing bout sheets.
FAQ
Is 6.35029318 exact or approximate?
Exact by composition. This tool uses 14 lb per stone and the 1959 international pound (0.45359237 kg), not a rough multiply-by-0.157 estimate.
Can I convert stone back to kilograms?
This capability is kilograms → stone only. Multiply stone by 6.35029318 on your side, or use a bidirectional mass converter for other units.
Is the kg to stone converter free?
The browser tool is free and runs locally.
How many stone is 70 kg?
70 kg is just over 11 stone, about 11.02311310924 with the exact division. In the UK and Ireland many people would describe that body weight simply as eleven stone.
Why not just multiply by 0.157?
Because 0.157 is a rounded shortcut. The exact path divides by 6.35029318, and the gap from rounding grows with the mass, so it shows on a body weight and even more on a load of several hundred kilograms.
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/kg-to-stone \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"kg":6.35029318}'const res = await fetch("https://api.kit.forhosting.com/conv/kg-to-stone", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"kg": 6.35029318
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/kg-to-stone",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"kg": 6.35029318
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/kg-to-stone", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"kg":6.35029318}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"kg":6.35029318}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/kg-to-stone", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"kg": 6.35029318
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.kg_to_stone",
"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 | 1000000000000 |
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 kg. Aliases kilograms, kilogrammes, value, mass, kg_value, and weight are accepted so SDK clients and form posts can use the name that fits the product. On success the response echoes rounded kg, sets stone, result, and converted to the same rounded stone magnitude, unit to the token st, from_unit to kg and to_unit to st, factor to the rounded reciprocal one over six point three five zero two nine three one eight, kg_per_stone to the exact constant six point three five zero two nine three one eight, pounds_per_stone to fourteen, formula to the string stone equals kg divided by six point three five zero two nine three one eight, message to a short English summary, and steps to an ordered array of substitution lines that show the fourteen-pound definition. 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 kg or pass text.
Integration use cases
Homework and unit-test fixtures
Students and engineers convert classroom kilogram masses to stone and pin golden JSON so browser and API arithmetic never drift.
Technical questions
What formula converts kg to stone?
Stone = kilograms ÷ 6.35029318. One stone is exactly fourteen international pounds, and one pound is exactly 0.45359237 kg, so 1 st = 6.35029318 kg.
What happens on missing or non-numeric input?
The API returns invalid_input naming the problem (for example a missing kg field). Failed tasks are not charged.