PSI to inches of water conversion
1 psi is 27.7076 inches of water, the conventional factor for a water column near 60 °F printed on many manometer charts. Turn gauge or compressor readings in psi into the water-column figures HVAC schedules, filter-drop tables and fan curves use. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Psi
- 1
- Result
- 27.7076 inH2O
- Converted
- 27.7076
- Inches of water
- 27.7076
- From unit
- psi
A psi-to-inches-of-water conversion turns a pressure written in pounds per square inch into the inches-of-water-column figure used on HVAC static-pressure schedules, manometer logs, filter-drop tables, fan curves, and many boiler or ductwork datasheets.
Why psi and inches of water still meet at a conventional factor
Pounds per square inch remain the everyday pressure unit on many United States gauges, compressor nameplates, hydraulic benches, and process instrumentation. Inches of water column remain the language of HVAC static pressure, manometer logs, filter-drop tables, fan-curve sheets, and low-pressure boiler or tank readings. The bridge between them is a single conventional multiplication: inches of water equals psi times twenty-seven point seven zero seven six.
That factor is the customary US engineering conversion for a water column near sixty degrees Fahrenheit, the temperature printed on many manometer charts and filter-drop tables. It is slightly larger than the four-degree-Celsius SI water-column factor near twenty-seven point six eight, because water is a little less dense at sixty Fahrenheit than at maximum density.
Teachers and some SI tables therefore quote a different constant; this landing hard-codes twenty-seven point seven zero seven six because that is the number people search for when they type psi to inches of water conversion, and it is the number many field gauges already assume. Zero psi maps cleanly to zero inches of water. Negative values are accepted as signed gauge-style deltas when a signed difference is meaningful to the caller.
The conversion is not a mixed-unit parser, not a temperature-dependent density solver, and not a general pressure hub: input is always psi and output is always inches of water.
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 psi and confirm you receive twenty-seven point seven zero seven six inches of water, convert two psi and confirm the result doubles to fifty-five point four one five two, or convert one half psi and confirm thirteen point eight five three eight.
When teaching, pair this conventional sixty-Fahrenheit factor with the colder four-degree-Celsius SI water-column factor so students see why two tables can disagree by a few hundredths of an inch per psi. 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 psi to inches of water conversion, convert psi to inH2O, or a water-column calculator from pounds per square inch; it is not a general multi-unit pressure hub, not an inches-of-water-to-psi 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 psi and you only need inches of water; if you must convert among many pressure-head units in one call, use a broader pressure-head converter instead.
What you can do with it
HVAC static pressure and filter drop
Turn a psi reading from a combined sensor or process sheet into the inches-of-water figure on a duct static-pressure schedule or filter-drop chart with the same conventional factor every row.
Homework and lab manometer checks
Students convert classroom psi values to inches of water and compare hand work against deterministic steps before submitting worksheets that must use 27.7076 inH2O per psi.
Boiler, tank, and process-sheet bridging
Technicians map psi-scale setpoints into inches-of-water expectations on low-pressure boiler, tank, and manometer instruments without hunting a printed conversion table.
FAQ
What factor converts psi to inches of water?
This converter multiplies the input psi by the conventional engineering factor 27.7076 inches of water per psi (a water column near 60 °F) and returns the pressure in inches of water.
Is 27.68 the same as 27.7076?
No. About 27.68 inH2O per psi is the colder 4 °C SI water-column ratio. This landing hard-codes 27.7076, the conventional US HVAC and manometer-chart factor.
What input field do I send?
Send a finite number in the field psi.
Is the psi to inches of water conversion free?
The browser tool is free and runs locally.
Where are inches of water used?
They are the usual unit for HVAC static pressure, manometer logs, filter pressure-drop tables and fan-curve sheets, and for low-pressure boiler or tank readings.
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/psi-to-inches-of-water-conversion \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"psi":1}'const res = await fetch("https://api.kit.forhosting.com/conv/psi-to-inches-of-water-conversion", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"psi": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/psi-to-inches-of-water-conversion",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"psi": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/psi-to-inches-of-water-conversion", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"psi":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"psi":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/psi-to-inches-of-water-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
{
"psi": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.psi_to_inches_of_water_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.
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
String numbers are accepted only when they match a strict finite numeric pattern; do not send unit suffixes such as psi or inH2O inside the numeric field itself. Classic checks include one psi mapping to twenty-seven point seven zero seven six inches of water and two psi mapping to fifty-five point four one five two. Send a JSON body with one required finite number field named psi. Aliases value, pressure, psi_value, and pounds_per_square_inch are accepted so SDK clients and form posts can use the name that fits the product. Absolute values must stay within the published limit of one trillion, and the converted inches-of-water magnitude must also stay inside that cap, so extremely large psi values fail as invalid_input rather than returning Infinity. On success the response echoes rounded psi, sets inches_of_water, result, and converted to the same rounded water-column magnitude, unit to the token inH2O, from_unit to psi and to_unit to inH2O, factor and inches_of_water_per_psi to the conventional constant twenty-seven point seven zero seven six, formula to the English equation inches of water equals psi times 27.7076, 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.
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 psi or pass text.
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.