How to use this calculator
- Enter usable altitude. Use altitude available to lose before reaching the target clearance.
- Enter glide ratio. Use aircraft data or a conservative training value.
- Enter glide speed. Use best-glide or the speed you want to check.
- Read distance and time. Treat the distance as still-air only.
How it works
The still-air estimate is
glide distance = usable altitude x glide ratio.
Written as a compact calculation, distance = altitude * glide ratio.
Descent angle is atan(1 / glide ratio), and the
entered airspeed gives time and sink rate.
Treat this as a glide ratio distance calculator or a best glide distance calculator only when your entered ratio and airspeed match the aircraft configuration you are actually flying. For an emergency landing glide range, subtract margin for headwind, turns, runway alignment, terrain, obstacles, configuration changes and reaction time.
Use it with wind components, climb gradient and density altitude.
Worked example
Verified against the live calculator
With 3,000 ft usable altitude and a 9:1 glide ratio, still-air range is about 27,000 ft, or roughly 4.4 nautical miles.
Frequently asked questions
How do you calculate glide distance?
Still-air glide distance is usable altitude multiplied by glide ratio.
What is the glide distance formula?
The glide distance formula is distance = usable altitude x glide ratio. Keep altitude and distance in compatible units, then convert the final range to miles, nautical miles or kilometers.
How do I use glide ratio for distance?
Multiply the usable altitude above the target by the glide ratio. For example, 3,000 ft at 9:1 gives 27,000 ft of still-air distance before wind, turns and maneuvering margin.
Is this a best glide distance calculator?
Yes, if the glide ratio and airspeed you enter are the aircraft’s best-glide values for the current configuration. It does not prove a safe emergency landing glide range because wind, turns, terrain, obstacles and pilot workload still need margin.
Does wind change glide distance?
Yes. This calculator is still-air only; headwind reduces ground range and tailwind increases it.
Why enter glide airspeed?
Airspeed is used for glide time and sink-rate estimates, not the still-air distance itself.
Should I enter total altitude?
Enter usable altitude above the terrain or target clearance, not just indicated altitude.
Method & assumptions
- Assumes still air and a steady glide ratio.
- Does not include turns, wind, configuration changes, propeller drag, terrain, obstacles or pilot workload.