Combined gas law final volume calculator
This combined gas law final volume calculator finds the final gas volume when both pressure and temperature change for a fixed amount of ideal gas.
Run — free
You supply the initial pressure P1, initial volume V1, initial absolute temperature T1, the new pressure P2, and the new absolute temperature T2; the engine returns the final volume V2 from the classical identity P1 times V1 over T1 equals P2 times V2 over T2, which rearranges to V2 equals P1 times V1 times T2 over P2 times T1. That identity is the combined gas law: Boyle and Charles in one proportion when the amount of gas is fixed. Worked checks include P1 equals one, V1 equals two, T1 equals three hundred, P2 equals two, T2 equals three hundred yielding V2 equals one, and P1 equals two, V1 equals five, T1 equals two hundred fifty, P2 equals one, T2 equals five hundred yielding V2 equals twenty. Temperatures must be absolute (typically Kelvin); zero P2 or zero T1 is rejected because the rearrange divides by those values. The path is pure finite arithmetic with no network calls, no sampling, and no date-dependent shortcuts. Use it free in the browser for homework, lab prep, and gas-law drills, or call the API at $0.002 per successful request when you need reproducible final-volume fixtures in CI, tutoring software, or teaching demos.
How to use it
Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.
Check your inputs
Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.
Use it again or automate it
Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.
What you can do with it
Get an answer now
Enter one set of values and see the result without building a spreadsheet or script.
Compare scenarios
Change one value at a time and rerun the calculation to understand what affects the result.
Automate repeated work
Use the API when the same calculation needs to run inside your product or workflow.
FAQ
How do I use this capability?
Complete the fields above and run it on this page. The form highlights anything that needs attention.
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/combined-gas-final-volume \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"P1":1,"V1":2,"T1":300,"P2":2,"T2":300}'const res = await fetch("https://api.kit.forhosting.com/chem/combined-gas-final-volume", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"P1": 1,
"V1": 2,
"T1": 300,
"P2": 2,
"T2": 300
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/chem/combined-gas-final-volume",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"P1": 1,
"V1": 2,
"T1": 300,
"P2": 2,
"T2": 300
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/combined-gas-final-volume", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"P1":1,"V1":2,"T1":300,"P2":2,"T2":300}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"P1":1,"V1":2,"T1":300,"P2":2,"T2":300}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/combined-gas-final-volume", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"P1": 1,
"V1": 2,
"T1": 300,
"P2": 2,
"T2": 300
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "chem.combined_gas_final_volume",
"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_value | 1000000000000000 |
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. |