Glide Ratio and Range Calculator
Calculate glide ratio, maximum glide range from altitude, minimum descent rate, and best glide speed for any aircraft.
Essential for engine failure planning.
Glide Ratio (L/D) The glide ratio (or lift-to-drag ratio, L/D) is the horizontal distance traveled per unit of altitude lost in a power-off glide. Glide ratio = L/D = Lift/Drag (dimensionless) In still air: Ground covered = Altitude × Glide ratio A glide ratio of 10:1 means the aircraft covers 10 units horizontally for every 1 unit of altitude lost.
Typical Glide Ratios Paper airplane: ~5:1 Light aircraft (Cessna 172): ~9:1 Jet airliner (Boeing 737): ~17:1 Business jet: ~15–20:1 Powered sailplane: ~40:1 High-performance glider: 50–70:1 Hang glider: ~12:1 | Paraglider: ~8–10:1
Best Glide Speed (Vbg) Best glide speed gives the maximum glide ratio (minimum drag, maximum L/D). Flying faster or slower than Vbg increases drag ratio and reduces range. In a headwind: increase speed above Vbg. In a tailwind: reduce speed toward Vstall + margin.
Minimum Sink Rate Minimum sink speed is slower than best glide speed — gives maximum time in the air. Used by glider pilots thermaling to stay in lift. Minimum sink = about 75–80% of best glide speed (roughly).
Wind Effect on Glide Headwind component reduces effective glide range. Effective ground glide ratio = (V_tas − V_headwind) / sink_rate For engine failure: adjust heading to minimize headwind, maximize groundspeed.
Engine Failure Emergency After engine failure, pilot should immediately establish best glide speed. Identify the highest reachable airport within glide range. Call mayday: 121.5 MHz (Emergency frequency). Glide range (no wind) = Altitude AGL × Glide ratio