Psig to psia converter
100 psig is 114.696 psia: add one conventional atmosphere of 14.696 psi to the gauge reading and you get the absolute pressure that gas-law, boiling-point and vacuum work need. Gauge zero is 14.696 psia. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Psig
- 100
- Result
- 114.696 psia
- Converted
- 114.696
- Psia
- 114.696
- From unit
- psig
A psig to psia converter turns a gauge pressure reading—the number a mechanical dial shows when it reads zero in open air—into absolute pressure by adding one conventional atmosphere of 14.696 psi. Process sheets, compressor nameplates, HVAC charts, scuba logs, and many United States laboratory notebooks mix the two families: psig for what the gauge shows, psia for thermodynamics, vacuum work, and ideal-gas calculations that must sit on an absolute scale that starts at a perfect vacuum.
Why gauge and absolute pressure differ by one atmosphere
Gauge pressure, written psig, is the excess of a fluid pressure over the surrounding air. A mechanical Bourdon tube, a tyre inflator, a compressor switch, and most HVAC manifold gauges are built so that they read zero when the port is open to the room; they do not know, and do not report, the fourteen-odd pounds of air sitting on every square inch of the planet. Absolute pressure, written psia, starts at a perfect vacuum.
Thermodynamics, the ideal-gas law, boiling-point tables, vacuum process specs, and any energy balance that uses specific volume need that absolute scale, because a gas at gauge zero is still at one atmosphere of real pressure. Converting psig to psia is therefore a single offset, not a unit scale: add one conventional atmosphere of 14.696 psi.
That rounded constant is the number printed on United States engineering worksheets, compressor nameplates, and classroom tables that ask for psig to psia conversion; it is not the pascal-derived 14.6959 figure, and it is not the coarser 14.7 mental shortcut. Zero psig maps to 14.696 psia, which is open-air absolute. A vacuum of minus five psig maps to 9.696 psia, still above a hard vacuum.
One hundred psig maps to 114.696 psia. Negative results can appear only if the gauge reading is more than one atmosphere below ambient; those values remain valid while they stay finite. Prefer this landing when the search is specifically psig to psia rather than a multi-unit pressure hub that would leave the atmospheric offset to you.
Practical tips, checks, and related searches
Prefer sending bare numbers when you control the client; paste-time strings with units will fail because the solver is a number converter, not a unit parser. Round-trip sanity checks are easy: convert zero psig and confirm you receive 14.696 psia, because gauge zero is one conventional atmosphere on the absolute scale; convert one hundred psig and confirm 114.696 psia; convert a vacuum of minus ten psig and confirm 4.696 psia, still above hard vacuum.
When teaching, pair this conventional 14.696 offset with the 14.7 mental shortcut and with the SI-derived 14.6959 figure so students see both rounding families without mixing them on the same worksheet. Stay inside the absolute range so the add cannot overflow into a non-finite result the solver must reject.
This landing targets people searching for psig to psia conversion, convert gauge pressure to absolute, or a psig to psia calculator that adds 14.696 psi; it is not a general multi-unit pressure hub, not a psia-to-psig primary form, not a bar-to-psig scale, not a vacuum torr converter, and not a tyre-load or scuba dive-table tool. Prefer this capability when the input is already in gauge pounds per square inch and you only need absolute pounds per square inch.
Pin the twelve-decimal rounded psia field in automated checks rather than re-adding 14.696 in the test harness, so a future change to the offset would fail loudly instead of silently.
What you can do with it
Compressor and process-sheet bridging
Turn gauge setpoints from United States compressor and HVAC sheets into psia fields for thermodynamics and vacuum specs with the same 14.696 psi offset every row.
Homework and lab report checks
Students convert classroom psig readings to absolute psi and compare hand work against deterministic steps that show the added conventional atmosphere.
Gauge zero versus open-air absolute
Technicians confirm that a dial reading of zero psig converts to 14.696 psia, matching ambient air on the absolute scale used by gas laws.
FAQ
How do you convert psig to psia?
Treat the input as gauge pressure in psig. Add one conventional atmosphere of 14.696 psi. The sum is absolute pressure in psia: psia = psig + 14.696.
Why add 14.696 instead of 14.7 or 14.6959?
Fourteen point six nine six is the conventional atmosphere printed on United States gauge-to-absolute worksheets. Fourteen point seven is a coarser classroom shortcut. The SI-derived atmosphere from 101325 Pa is about 14.6959 psi. This converter uses 14.696 so search intent and worksheet arithmetic match.
What does 0 psig convert to?
Zero psig is open-air gauge zero, so the result is 14.696 psia—one conventional atmosphere on the absolute scale.
Can I convert a vacuum (negative psig)?
Yes. Negative gauge pressure is vacuum relative to ambient air. Adding 14.696 still yields absolute pressure, which stays positive until the gauge reading is more than one atmosphere below ambient.
Is the psig to psia converter free?
The browser tool is free and runs locally.
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/psig-to-psia-conversion \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"psig":100}'const res = await fetch("https://api.kit.forhosting.com/conv/psig-to-psia-conversion", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"psig": 100
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/psig-to-psia-conversion",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"psig": 100
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/psig-to-psia-conversion", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"psig":100}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"psig":100}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/psig-to-psia-conversion", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"psig": 100
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.psig_to_psia_conversion",
"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 reading.
How to call the API and what comes back
The value is treated as gauge pressure in pounds per square inch; do not send an already-absolute psia reading unless you intend to add atmosphere a second time. Absolute values must stay within the published limit of one trillion. String numbers are accepted only when they match a strict finite numeric pattern, without units, thousand separators, or trailing labels such as psig. Send a JSON body with one required finite number field named psig. Aliases value, pressure, gauge, gauge_pressure, and psig_value are accepted so SDK clients and form posts can use the name that fits the product. On success the response echoes rounded psig, sets psia, result, and converted to the same rounded absolute magnitude, unit to the token psia, from_unit to psig and to_unit to psia, atm_psi to the conventional offset 14.696, formula to the short English equation psia equals psig plus 14.696, 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. Keep payloads small and pin expected psia values in tests so continuous integration never drifts across runtimes.
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 psig or pass text.