What cruise speed is the fuel reserve based on a Cessna 172?

The fuel reserve for a Cessna 172 is typically based on a cruise speed of approximately 100 knots (about 115 mph or 185 km/h). This speed is used to calculate the time the aircraft can remain airborne after reaching its destination, ensuring a safe reserve for unforeseen circumstances. The standard fuel reserve is usually set at 30 minutes of flight time, allowing for safe landings in case of unexpected delays.