Glide distance from altitude
Find how far an aircraft can glide without power: 1000 metres above the field with a 10 to 1 glide ratio gives a still-air reach of 10 kilometres, also shown in statute and nautical miles. Free in your browser.
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Worked example
- Altitude
- 1,000
- Glide ratio
- 10
- Altitude unit
- M
- Distance unit
- Km
- Glide distance
- 10
- Glide distance m
- 10,000
- Glide distance km
- 10
- Glide distance mi
- 6.2137119224
When an engine fails, a glider leaves the ridge, or a student plans a forced landing, the first number that matters is how far the aircraft can still reach. Glide distance from altitude multiplies height above the intended touchdown elevation by the best glide ratio L/D to give the maximum still-air horizontal range without power. This calculator accepts altitude, a positive glide ratio, and optional length units for input height and output range, then returns the primary glide distance, the same range in metres, kilometres, statute miles, and nautical miles, the glide path angle below the horizontal, and the sink ratio one over L/D.
What glide distance means and the still-air formula
A glide ratio of ten to one means that for every unit of altitude lost in a coordinated, best-glide configuration, the aircraft travels ten units of horizontal distance through the air mass. In still air with no wind, that air distance equals ground range, so the maximum reachable distance without power is simply altitude times glide ratio. If you are one thousand metres above the landing elevation with a ten-to-one L/D, the theoretical circle of reach has a ten-kilometre radius on flat terrain.
The reciprocal sink ratio one over L/D is the vertical over horizontal slope used in some performance tables. Wind, density altitude effects on true airspeed, turns, configuration drag, and terrain that rises under the path all shrink the real footprint relative to this ideal number, which is why pilots treat the result as an upper bound for planning and training rather than a guarantee of reaching a runway.
Who uses a glide distance calculator
Flight schools and simulator sessions use a glide distance calculator so students can see how height above a field multiplies into a planning radius before they memorise rule-of-thumb charts. Glider and hang-glider pilots estimate landing options from thermalling height and a published polar L/D without opening a full performance workbook. Content sites that rank for glide distance from altitude or glide ratio range benefit from a live free browser tool whose math matches the automation path byte for byte.
Drone and RC soarers apply the same geometry when altitude above home and a measured L/D set the return-to-home budget in still air. Keep requests small, pin the cleaned floats in tests, and you get reproducible still-air ranges for lessons, apps, and edge workers without standing up a full flight-dynamics stack of your own.
What you can do with it
Engine-out and forced-landing drills
Convert height above a candidate field and the aircraft best L/D into a still-air reachable radius for briefing and debrief without a full performance app.
Glider and soaring planning
Estimate max ground range from thermalling altitude and polar glide ratio before choosing a landing option or final glide.
Training content and LMS checks
Auto-grade altitude × L/D problems with a deterministic oracle that rejects non-positive inputs and returns multi-unit distances.
FAQ
How is maximum glide distance calculated from altitude?
In still air the horizontal range without power is altitude multiplied by the glide ratio L/D. Example: 1000 m at 10:1 yields 10 000 m (10 km) of ground range on flat terrain.
What is a glide ratio (L/D)?
The lift-to-drag ratio at best glide. A value of 15 means fifteen units of horizontal travel per unit of altitude lost. Enter it as a positive number (15), not as a fraction string.
Does wind change the result?
This calculator assumes zero wind and constant L/D. Headwind shortens ground range and tailwind lengthens it; treat the output as the ideal still-air maximum for planning.
Which altitude should I use?
Use height above the intended landing elevation (or terrain under the path), not necessarily altitude above mean sea level. Only the height you can afford to lose contributes to range.
What do the glide angle and the sink ratio tell me?
Both come from the same L/D. The sink ratio is one divided by L/D, so 10 to 1 gives 0.1, and the glide angle is the arctangent of that slope, in degrees below the horizontal, as used in briefings and charts.
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/geo/glide-distance \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"altitude":1000,"glide_ratio":10}'const res = await fetch("https://api.kit.forhosting.com/geo/glide-distance", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"altitude": 1000,
"glide_ratio": 10
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/geo/glide-distance",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"altitude": 1000,
"glide_ratio": 10
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/geo/glide-distance", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"altitude":1000,"glide_ratio":10}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"altitude":1000,"glide_ratio":10}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/geo/glide-distance", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"altitude": 1000,
"glide_ratio": 10
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "geo.glide_distance",
"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
Failed validation is not billed; successful calls use prepaid KIT balance at the published base price.
What glide distance means and the still-air formula
The glide path angle below the horizontal follows from the same ratio: the arctangent of one divided by the glide ratio converts the slope into degrees for briefings and charts. Real aircraft also have a published best-glide indicated airspeed; this endpoint does not solve energy or time of flight—it only converts altitude and a constant L/D into geometric range.
Input contract, units, response shape, and errors
Pair the response with your own map circle if you need a geographic footprint; this capability is pure range arithmetic. POST a JSON body with two required positive finite numbers: altitude, the height above the intended landing elevation (not necessarily mean sea level), and glide_ratio, the best L/D as a pure number such as ten for ten-to-one. Optional altitude_unit defaults to metres and accepts m, ft, km, mi, or nmi. Optional distance_unit selects the unit for the primary glide_distance field; when omitted it matches altitude_unit so a feet input yields a feet range without extra conversion. On success the body echoes altitude, altitude_unit, and glide_ratio; returns glide_distance and distance_unit; always includes glide_distance_m, glide_distance_km, glide_distance_mi, and glide_distance_nmi for multi-unit UIs; and adds glide_angle_deg, sink_ratio, a formula string, and a short assumptions note stating still air, constant L/D, zero wind, unpowered flight, and flat Earth over the range of interest. Missing fields, non-finite values, zero or negative altitude or glide ratio, and unknown unit strings fail with invalid_input naming the problem and are not billed. Example: altitude one thousand, glide_ratio ten, altitude_unit m, distance_unit km yields glide_distance ten kilometres, ten thousand metres, about six point two one statute miles, about five point four nautical miles, and a glide angle near five point seven one degrees.
Technical questions
What does the glide distance calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.