Glide Ratio Calculator

About this calculator

Glide ratio (also called the lift-to-drag ratio in a steady glide) is simply the horizontal distance an aircraft travels for every unit of altitude it loses with no engine power — a glide ratio of 10:1 means 10 meters of forward travel for every 1 meter of descent. A typical single-engine trainer like a Cessna 172 glides at roughly 9:1, while modern competition sailplanes are optimized to exceed 60:1, and the difference comes down to wingspan, wing loading, and aerodynamic drag.

Pilots use glide ratio to calculate how far they can travel after an engine failure — a critical number in the "best glide speed" procedure taught in every private pilot curriculum for picking a landing site within reach — and glider and sailplane pilots use it continuously in flight to judge whether they can reach the next thermal or the airport. The same distance-per-altitude-lost concept is used in wingsuit flying and hang gliding to plan a flight path.

This calculator takes horizontal distance traveled and altitude lost and returns the glide ratio.