Bar to PSI converter
One bar, exactly 100,000 pascals, is 14.503773773021 psi. This converter applies that full factor instead of a rounded 14.5, so European tyre placards, boiler gauges and compressor datasheets line up with US gauges and process sheets. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Bar
- 1
- Result
- 14.503773773 psi
- Converted
- 14.503773773
- Psi
- 14.503773773
- From unit
- bar
A bar-to-psi converter turns a metric bar pressure reading into the pounds-per-square-inch value used on tyre gauges, compressor nameplates, hydraulic benches, scuba charts, and many United States process sheets. Rough classroom shortcuts such as multiply by fourteen point five are rejected in favour of the full SI-derived constant, so homework checks and catalog exports match engineering tables.
Why bar and psi still meet at an exact factor
Bar is the everyday metric pressure unit on European tyre placards, industrial process sheets, boiler gauges, and many compressor datasheets. One bar is defined as exactly one hundred thousand pascals—ten to the fifth power—so it sits cleanly next to the SI pascal without an awkward decimal. Pounds per square inch remain the everyday pressure unit on many United States tyre placards, air-tool ratings, hydraulic benches, and process instrumentation.
The bridge between them is not a memorised fourteen point five rule of thumb: one bar is exactly one hundred thousand pascals, and one pound-force per square inch follows from the international avoirdupois pound, standard gravity nine point eight zero six six five metres per second squared, and the exact inch of zero point zero two five four metres. That makes the conversion a single exact multiplication, psi equals bar times the ratio of those two pressure scales.
Teachers and field techs often still teach multiply by fourteen point five, but that truncates several significant figures and drifts on multi-bar compressor stages or laboratory gauge chains. Prefer the exact path whenever your audience will compare against engineering tables rather than mental arithmetic.
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 bar and confirm you receive about fourteen point five zero three seven seven three seven seven three zero two one psi after rounding, or convert two bar and confirm the result doubles within the same twelve-decimal policy.
When teaching, pair the exact path with the fourteen point five mental shortcut so students see the truncated error on multi-bar stages. Stay inside the absolute range so the multiply cannot overflow into a non-finite result the solver must reject. This landing targets people searching for bar to psi, convert bar to psi, or an exact bar pressure calculator; it is not a general multi-unit pressure hub, not a psi-to-bar primary form, not a vacuum torr converter, and not a tyre-load or scuba dive-table tool.
Prefer this capability when the input is already in bar and you only need psi; if you must convert among many pressure units in one call, use a broader pressure converter instead.
What you can do with it
Compressor and process-sheet unit bridging
Turn bar setpoints from European or metric datasheets into psi fields on US equipment sheets with the same exact factor every row.
Homework and lab report checks
Students convert classroom bar readings to psi and compare hand work against deterministic steps before submitting worksheets.
Tyre, hydraulic, and gauge cross-checks
Hobbyists and technicians map bar-scale gauges into psi expectations without relying on a rounded 14.5 shortcut.
FAQ
What factor converts bar to psi?
One bar is 100000 Pa exactly. One psi is one pound-force per square inch from the international pound, standard gravity, and the exact inch. The tool multiplies bar by that exact SI-derived ratio (about 14.503773773021).
Is 14.5 psi per bar exact?
No. 14.5 is a common classroom rounding. This converter uses the full SI-derived factor so results match engineering tables after fixed twelve-decimal rounding.
What input field do I send?
Send a finite number in the field bar.
Is the bar to psi converter free?
The browser tool is free and runs locally.
Where is bar used, and where is psi?
Bar appears on European tyre placards, boiler gauges, industrial process sheets and many compressor datasheets. Psi is the everyday unit on US tyre placards, air-tool ratings and hydraulic benches, which is why the same pressure often needs both.
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/bar-to-psi \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"bar":1}'const res = await fetch("https://api.kit.forhosting.com/conv/bar-to-psi", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"bar": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/bar-to-psi",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"bar": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/bar-to-psi", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"bar":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"bar":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/bar-to-psi", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"bar": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.bar_to_psi",
"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. When embedding in scripts, treat the response as pure data: read psi or result for the magnitude, and use steps only when you want human-readable audit text. Keep clients tolerant of extra fields so future additive metadata does not break parsers. Send a JSON body with one required finite number field named bar. Aliases bars, value, pressure, and bar_value are accepted so SDK clients and form posts can use the name that fits the product. On success the response echoes rounded bar, sets psi, result, and converted to the same rounded pound-per-square-inch magnitude, unit to the token psi, from_unit to bar and to_unit to psi, factor and psi_per_bar to the rounded exact conversion factor, pa_per_bar to the integer one hundred thousand, formula to a short English equation string, message to a brief summary, and steps to an ordered array of substitution lines. 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 bar or pass text. Document the factor in lab notebooks next to the numerical result so reviewers can recompute offline without opening the API again.
Technical questions
What happens on invalid input?
Missing fields, non-finite numbers, or values outside the absolute limit return invalid_input. Failed tasks are never charged.