Glide Ratio Calculator

How it is calculated

The tool divides the horizontal distance covered by the height lost: glide ratio = distance ÷ altitude lost, shown as x : 1. It also gives the glide angle below the horizontal, angle = arctan(altitude lost ÷ distance), in degrees. Both values are rounded to two decimals. Distance and altitude must both be above zero. The ratio is unitless as long as both are entered in the same unit. The metres/feet selector does not change the arithmetic, so 15000 and 600 give the same answer in either unit. The result describes the glide you measured. It does not correct for wind, turns or changes in speed, and a ratio measured in still air will differ from one measured with a headwind.

Common mistakes

• Mixing units, such as distance in kilometres and altitude in metres. A 15 km glide with 600 m lost typed as 15 and 600 gives 0.03 : 1, not 25 : 1.
• Using distance flown through the air instead of horizontal ground distance. The ratio needs the horizontal distance only.
• Entering the total height of the flight rather than the height lost. If you started at 1500 m and landed at 900 m, the altitude lost is 600 m.
• Turning the ratio upside down. 25 : 1 means 25 units forward per unit down, and the glide angle is the flat 2.29°, not 25.
• Treating a ratio from one flight as fixed. Wind, speed and configuration change it, so a measured value is only valid for those conditions.