Aviation oxygen duration calculator
A 600-litre bottle at 1,500 of 1,800 psi holds 500 usable litres, enough for 125 minutes when two people each breathe 2 litres per minute. Check it before an unpressurized climb. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Capacity
- 600
- Users
- 2
- Flow rate
- 2
- Pressure
- 1,500
- Result
- 125
- Capacity unit
- Liters
- Capacity liters
- 600
- Pressure unit
- Psi
How long will the portable oxygen bottle last once cabin altitude or mountain terrain pushes you above the level where supplemental oxygen is required?
What aviation oxygen duration means and how the Boyle ratio works
A portable aviation oxygen bottle does not empty at a clock rate stamped on the cylinder. Remaining endurance is the usable oxygen still inside divided by how fast the crew is breathing it. Usable oxygen is not the stamped capacity by itself: capacity is the full-charge volume of oxygen the bottle holds at its service pressure, and the gauge tells you what fraction of that charge is left.
Boyle's law at cabin temperature says that the volume of free oxygen scales with the pressure ratio, so usable litres equal capacity converted to litres times remaining pressure minus any residual reserve, all divided by full service pressure. Demand is the altitude flow rate in litres per minute per person multiplied by the number of users sharing the regulator or the built-in ports. Duration in minutes is usable litres divided by that total flow.
The altitude flow rate is the planning number from your cannula or mask table—typically about one litre per minute in the low teens of thousands of feet and two or more litres per minute as you climb toward the flight levels—not a guess from ground-level breathing. This calculator applies that identity exactly. It does not invent a regulatory oxygen requirement, choose a mask for you, or derate a leaking bottle; you bring capacity, users, the flow you will actually use at altitude, and the pressure you read on the gauge.
Who checks oxygen time before a flight
General-aviation pilots and instructors use an aviation oxygen duration calculator before unpressurized cross-countries above twelve thousand five hundred feet so the portable bottle is not assumed to last the entire estimated time en route when two people are on continuous flow. Mountain and high-altitude sightseeing operators need the same four-term check when a half-empty gauge meets a higher cruise flow.
Charter and flight-school dispatch desks already hold cylinder capacity, occupant count, the flow they brief for the planned cabin altitude, and the pressure they read at the hangar; they do not need a full flight-planning suite to turn those four numbers into minutes. Training organisations and checkride briefings need a deterministic oracle that treats remaining pressure as a Boyle fraction of full-charge volume, accepts litres or cubic feet, and never silently drops a second occupant.
What you can do with it
Unpressurized cross-country above 12,500 ft
Turn cylinder capacity, remaining psi, planned L/min, and occupant count into minutes of oxygen before you leave the ramp.
Two-place portable bottle briefing
See how sharing a half-full bottle at a higher altitude flow cuts endurance versus a solo flight at one litre per minute.
Flight-school and checkride oxygen planning
Let students verify that remaining pressure is a Boyle fraction of full-charge volume and that duration scales with users and flow.
FAQ
What flow rate should I use at altitude?
Use the continuous-flow or cannula figure for the cabin altitude you will actually fly, typically about 1 L/min in the low teens of thousands of feet and 2 L/min or more higher up.
Why does remaining pressure matter if I already know capacity?
Capacity is the full-charge oxygen volume at service pressure. A half-full gauge holds about half that volume.
Can I enter capacity in cubic feet instead of litres?
Cubic feet of oxygen when full are converted at 28.316846592 litres per cubic foot before the pressure ratio is applied. Pressure may be psi (default) or bar.
How do I account for the reserve I leave in the bottle?
Enter the reserve pressure you do not plan to use, often 200 psi. It is taken off the gauge reading before the calculation, so the minutes you get already exclude that leftover.
Does the calculator tell me when oxygen is required or which mask to use?
No. It only turns capacity, pressure, flow and the number of users into minutes. It sets no regulatory requirement, does not pick a mask and does not discount a bottle that leaks.
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/travel/oxygen-duration \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"capacity":600,"users":2,"flow_rate":2,"pressure":1500}'const res = await fetch("https://api.kit.forhosting.com/travel/oxygen-duration", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"capacity": 600,
"users": 2,
"flow_rate": 2,
"pressure": 1500
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/travel/oxygen-duration",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"capacity": 600,
"users": 2,
"flow_rate": 2,
"pressure": 1500
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/travel/oxygen-duration", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"capacity":600,"users":2,"flow_rate":2,"pressure":1500}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"capacity":600,"users":2,"flow_rate":2,"pressure":1500}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/travel/oxygen-duration", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"capacity": 600,
"users": 2,
"flow_rate": 2,
"pressure": 1500
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "travel.oxygen_duration",
"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
This aviation oxygen duration calculator answers that briefing question from four numbers every unpressurized crew already has on the cylinder stamp and the gauge: bottle capacity, the number of users sharing the regulator, the altitude flow rate in litres per minute per person, and the pressure remaining. It applies Boyle's law as a pressure ratio against the cylinder's full-charge volume, divides the usable oxygen by total demand, and returns duration in minutes and hours. Missing or non-finite inputs fail with invalid_input and are not billed.
What aviation oxygen duration means and how the Boyle ratio works
Optional reserve_pressure models the unusable heel some operators leave in the bottle, commonly two hundred psi, without changing the four required inputs when you omit it.
Input contract, units, and response fields
Values are rounded to twelve decimal places for stable goldens. Example: six hundred litres, two users, two litres per minute each, and one thousand five hundred psi remaining on an eighteen-hundred-psi bottle yields five hundred usable litres and one hundred twenty-five minutes. POST a JSON body with four required finite numbers: capacity, the bottle's full-charge oxygen volume; users, a positive integer count of people drawing from the bottle; flow_rate, the altitude oxygen flow in litres per minute per person; and pressure, the gauge pressure remaining. Optional capacity_unit is liters by default or cu_ft when the cylinder is stamped in cubic feet of oxygen when full. Optional pressure_unit is psi by default or bar; it applies to pressure, full_pressure, and reserve_pressure together. Optional full_pressure is the rated service pressure and defaults to one thousand eight hundred psi, or the bar equivalent of that fill, matching a common portable aviation bottle. Optional reserve_pressure is the unusable residual, defaulting to zero. Each numeric field may arrive as a JSON number or as a numeric string; missing fields, empty strings, non-finite values, a non-positive capacity or flow_rate, a non-positive-integer users count, a negative pressure, and a reserve that is not strictly below full_pressure fail with invalid_input naming the field and are not billed. On success the body echoes the cleaned inputs, reports capacity_liters and the Boyle pressure_ratio, then usable_liters, total_flow_lpm, duration_minutes, duration_hours, duration_seconds, whole hours, leftover_minutes, and result as an alias of duration_minutes. A formula string restates the identity, method is boyle_pressure_ratio_over_flow, and message summarises the endurance in plain language.
Where an aviation oxygen duration API earns its keep
Engineering notebooks that already store cylinder size and gauge readings can call a tiny parse API instead of re-deriving the same arithmetic in every language binding. Keep requests small, pin duration_minutes and usable_liters in tests, and you get reproducible bottle time for briefings, LMS plugins, and edge workers without standing up a physiological-oxygen library of your own.
Technical questions
How do I calculate how long an aviation oxygen bottle lasts?
Send capacity (full-charge volume), users (positive integer), flow_rate in L/min per person, and remaining pressure. Duration in minutes is usable litres—capacity times (pressure minus reserve) over full_pressure—divided by flow_rate times users.
What does the aviation oxygen duration calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.