Molar volume at STP calculator
One mole of ideal gas at 0 °C and 1 atm fills 22.414 L, so any amount in moles becomes a volume in litres and cubic metres in one step. Enter the moles; the standard conditions are already fixed. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Moles
- 1
- Stp temperature K
- 273.15
- Stp pressure Pa
- 101,325
- Gas constant
- 8.314462618
- Molar volume m3 per mol
- 0.0224139695
At standard temperature and pressure, every mole of ideal gas occupies the same fixed molar volume, so the total gas volume is simply the product of that molar volume and the amount of substance in moles. This calculator uses the classic chemistry STP definition—zero Celsius and one atmosphere—together with the SI gas constant to form Vm equals R T over P, then multiplies by your moles to return the total volume in both cubic metres and litres. One mole yields the familiar twenty-two point four litres; two moles double it; fractional moles scale linearly. Negative amounts of substance are rejected as invalid input because they are non-physical under the ideal-gas model.
How volume at STP follows from the ideal-gas law
Start from the ideal-gas law P V equals n R T. At a fixed standard state the pressure and temperature stop being free variables, so the ratio R T over P becomes a constant molar volume Vm, and the total volume collapses to V equals n times Vm. This calculator locks classic chemistry STP: absolute temperature two hundred seventy-three point one five kelvin (zero degrees Celsius) and absolute pressure one hundred one thousand three hundred twenty-five pascals (exactly one atmosphere).
With the SI gas constant eight point three one four four six two six one eight joules per mole per kelvin, Vm evaluates to about zero point zero two two four one four cubic metres per mole, or about twenty-two point four one four litres per mole—the number every general-chemistry worksheet quotes. Multiplying by n moles therefore recovers the total volume without asking the student to re-enter P and T every time.
The tool does not use the one-bar IUPAC STP revision, does not accept custom pressure or temperature (those belong on a free ideal-gas molar-volume landing), does not convert mass or grams to moles, and does not apply compressibility factors for real gases. Negative moles fail with invalid input instead of inventing a negative volume. Zero moles is allowed and cleanly returns zero volume.
Where STP volume calculations show up in real work
Secondary-school and first-year university chemistry courses constantly assign problems that state how many moles of gas were collected and ask for the volume at STP before students learn full ideal-gas rearrangements. Stoichiometry chapters convert reaction yield in moles into litres of gas product at STP using the same n times twenty-two point four shortcut, and teachers need one trusted oracle for answer keys.
Environmental and industrial lab techs often report gas quantities as standard cubic metres or standard litres at a fixed reference state so inventory figures stay comparable across seasons; a deterministic STP volume tool is the first sanity check before more elaborate ISO standard-condition libraries. Contest and interview warm-ups still hide “how many litres does two moles occupy at STP” under mixture and eudiometry stories, and a hard rejection of negative moles prevents silent garbage.
Keep free-variable molar volume Vm equals R T over P on its own landing when the search intent is volume per mole at arbitrary P and T, and keep gas moles from pressure volume temperature on a separate page when the student already has measured V: those formulas share the gas constant but answer different homework questions and different SEO queries.
What you can do with it
Homework and STP answer keys
Convert textbook mole counts into litres and cubic metres at classic chemistry STP so teachers and auto-graders share one ground truth, including negative-moles rejection.
Stoichiometry gas-product volumes
Turn reaction-yield moles into STP gas volume for eudiometry, balloon, and cylinder sizing problems before introducing full PV=nRT rearrangements.
FAQ
What formula does this molar volume at STP calculator use?
Equivalently V = n · Vm_stp with Vm_stp ≈ 22.414 L/mol.
What happens if moles is negative?
Amount of substance cannot be less than zero under the ideal-gas volume-at-STP model.
Is this the same as the free molar volume calculator (Vm = RT/P)?
No. That tool takes arbitrary pressure and temperature for one mole. This tool takes only moles and multiplies by the fixed STP molar volume—different homework questions and different search intent.
Which STP definition is used—1 atm or 1 bar?
Classic chemistry STP: 0 °C and 1 atm (101325 Pa), which recovers the familiar ~22.4 L/mol. The one-bar IUPAC standard is not used here.
What does it cost?
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/chem/molar-volume-at-stp \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"moles":1}'const res = await fetch("https://api.kit.forhosting.com/chem/molar-volume-at-stp", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"moles": 1
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/molar-volume-at-stp",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"moles": 1
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/molar-volume-at-stp", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"moles":1}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"moles":1}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/molar-volume-at-stp", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"moles": 1
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.molar_volume_at_stp",
"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
What you send and what you get back
Zero is accepted; negative values fail with a message that moles must not be negative. Classic textbook checks include one mole recovering roughly twenty-two point four litres, two point five moles scaling linearly, and a deliberately negative mole count that must hard-fail. If you later need molar volume at arbitrary pressure and temperature, moles from P V T, or mass density from molar mass, treat those as separate search intents and landings rather than overloading this STP volume calculator page. Send a single required field named moles: a finite number for the amount of ideal gas in moles. Missing moles, empty strings, non-numeric text, NaN, and Infinity all fail with invalid_input and are not charged. On success the response echoes the cleaned moles, reports the fixed STP temperature in kelvin and pressure in pascals, echoes the SI gas constant, and returns both molar_volume_m3_per_mol and molar_volume_L_per_mol so you can see the twenty-two point four litre figure without converting units by hand. Total volume appears twice as volume_m3 and volume_L for SI lab notebooks and litre-based worksheets. A units map, the formula string V equals n times R times T_stp over P_stp, method molar_volume_at_stp, and a short stp_definition string document the fixed state so clients never guess whether one atmosphere or one bar was used. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.
Where STP volume calculations show up in real work
Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Curriculum widgets and API fixtures
Drive browser demos and CI golden tests from the same isomorphic solver so classroom tools never disagree with backend grading on n × 22.4 L.