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 distance estimate is range = altitude x glide ratio. Descent angle is atan(1 / glide ratio), and the entered airspeed gives time and sink rate.
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.
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.