ForHosting KIT · Science

Pounds per square inch converter

One psi is about 6894.757293168 pascals, or 0.068947572932 bar. Type a tyre, compressor or hydraulic reading in pounds per square inch and get pascals, bar and standard atmospheres at once, from the exact pound-force and inch. Free in your browser.

Free
Runs in your browser
No sign-up
Your data stays on your device

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

Worked example

If you enter

Psi: 1

You get

Pascals: 6,894.7572931684
Bar: 0.0689475729
Atmospheres: 0.0680459639
Pa per psi: 6,894.7572931684

Pounds per square inch, written psi, is the everyday US customary pressure unit on tyre gauges, compressor tanks, hydraulic benches, and process piping. This converter accepts a finite psi value and returns the same pressure in pascals, bar, and standard atmospheres using exact SI definitions of the pound-force, the inch, the bar, and the standard atmosphere. Pascals are the coherent SI unit of pressure; bar is the convenient one-hundred-thousand-pascal engineering unit; atmospheres rest on the one-hundred-one-thousand-three-hundred-twenty-five-pascal convention used in chemistry and meteorology.

What pounds per square inch means and which exact factors apply

Pounds per square inch measures force per area in the US customary system: one psi is one pound-force acting on one square inch. That sounds like a classroom shortcut until you pin the two definitions that make the conversion exact. The international avoirdupois pound is exactly 0.45359237 kilograms, standard gravity gₙ is exactly 9.80665 metres per second squared, and the international inch is exactly 0.0254 metres.

One pound-force is therefore that mass times gₙ, and one psi is that force divided by the square of the inch. The product is a fixed number of pascals, the SI unit of pressure, with no lookup table and no rounded 6895 shortcut hiding in the arithmetic. Once the pressure is in pascals, bar and atmospheres follow from two more exact constants: one bar is exactly 100000 pascals, and one standard atmosphere is exactly 101325 pascals by the CGPM convention used in gas laws and meteorology.

Negative psi is allowed because a gauge can read below atmospheric as a vacuum offset; zero psi converts to zero in every target unit. This landing does not convert torr, millimetres of mercury, kilopascals as a primary output, or gauge-to-absolute offsets, and it does not accept a free-form unit string. You send pounds per square inch; you receive pascals, bar, and atmospheres.

Keep the factor pinned in tests so homework, LMS plugins, and edge workers stay reproducible without standing up a units library of your own.

Where a pounds-per-square-inch converter earns its keep

Workshops and fleet bays still print tyre, compressor, and hydraulic pressures in psi, while lab notebooks, PLC tags, and chemistry problems expect pascals, bar, or atmospheres. A dedicated pounds-per-square-inch landing captures that search as a one-shot conversion instead of a general unit picker with a from-and-to dropdown. Exam-prep generators need a deterministic oracle that marks a non-finite input as invalid rather than silently returning NaN that a buggy grader might treat as success.

Process sketches that quote a vessel at 30 psi can emit the matching pascal, bar, and atmosphere values in one call without pulling a full units library. Failed validation does not consume balance. Keep requests small, pin the rounded pascals, bar, and atmospheres in tests, and you get reproducible conversions for homework, LMS plugins, and edge workers without standing up a metrology stack of your own.

Gauge-to-absolute offsets, temperature-dependent gas-law rearrangements, and conversions that start from bar or pascals remain outside this landing, so treat the numbers as the exact SI image of the psi you sent.

What you can do with it

Tyre, compressor, and hydraulic gauges

Convert a psi reading from a tyre, compressor, or hydraulic gauge into pascals, bar, and atmospheres for SI reports and mixed-unit work orders.

Lab notebooks and process sketches

Drop a vessel or line pressure quoted in psi into pascals, bar, and atmospheres without importing a full units library.

Homework and exam generators

Mark pounds-per-square-inch conversion items with a deterministic oracle that rejects non-finite input and never invents rounded classroom shortcuts.

FAQ

Which conversion factors does this pounds-per-square-inch calculator use?

One psi is one pound-force per square inch from the exact avoirdupois pound, standard gravity 9.80665 m/s², and the 0.0254 m inch. One bar is exactly 100000 Pa. One standard atmosphere is exactly 101325 Pa.

Can I convert a negative psi reading such as a vacuum gauge offset?

Yes. Negative psi is a valid finite pressure offset and converts with the same exact factors. Zero psi converts to zero pascals, zero bar, and zero atmospheres.

What happens if the input is not a finite number?

Missing fields, empty strings, NaN, and infinities are rejected and are not billed.

Can it convert psi to kPa, torr or mmHg?

No. The converter gives pascals, bar and standard atmospheres only. For kilopascals, torr or millimetres of mercury, use a dedicated converter, or take the pascal figure into your own unit picker.

Does it turn a gauge reading into absolute pressure?

No. It converts the number exactly as you type it and adds no atmospheric offset. A gauge reading stays a gauge reading in pascals, bar and atmospheres.

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

POSThttps://api.kit.forhosting.com/phys/pounds-per-square-inch

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/phys/pounds-per-square-inch \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"psi":14.7}'

const res = await fetch("https://api.kit.forhosting.com/phys/pounds-per-square-inch", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "psi": 14.7
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/phys/pounds-per-square-inch",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "psi": 14.7
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/phys/pounds-per-square-inch", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"psi":14.7}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"psi":14.7}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/phys/pounds-per-square-inch", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "psi": 14.7
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "phys.pounds_per_square_inch",
  "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

Per request$0.002

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 path is pure arithmetic with no network, no clock, and no randomness, so homework checks, lab notebooks, and API clients always receive the same JSON.

Input contract, response shape, and error behaviour

Absolute values larger than one trillion are rejected so a stray exponent cannot overflow the twelve-decimal rounding used for stable goldens. On success the body echoes the cleaned psi, reports pascals from the exact pound-force over square-inch definition, reports bar as those pascals divided by one hundred thousand, and reports atmospheres as those pascals divided by 101325. Example: one psi is about 6894.757293168 pascals, about 0.068947572932 bar, and about 0.06804596391 atmospheres, matching sibling converters that use the same SI definitions. POST a JSON body with one required finite number named psi, the pressure in pounds per square inch. The field may arrive as a JSON number or as a numeric string; aliases pounds_per_square_inch, value, and pressure are accepted so notebooks and gauge exports map without renaming columns. Missing fields, empty strings, NaN, and infinities fail with invalid_input naming psi, because a non-finite input is not a pressure. It also returns pa_per_psi, the rounded exact factor, a formula string restating the three relations, and a short message you can show next to the answer. Pair the response with your own unit picker if you need torr or millimetres of mercury; this endpoint converts psi to pascals, bar, and atmospheres only. The free browser form uses the same pure module as the API path, so a homework check and a production script never disagree on the twelfth decimal. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.

Technical questions

How do I convert pounds per square inch to pascals, bar, and atmospheres?

Send a finite number in the field psi (aliases pounds_per_square_inch, value, pressure). The API returns pascals from the exact lbf/in² definition, bar as pascals divided by 100000, and atmospheres as pascals divided by 101325.

What does the pounds-per-square-inch converter cost?

The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.

Read the full KIT documentation →

Run — free