What units is the altimeter setting recorded in?

The altimeter setting is recorded in inches of mercury. This unit is widely used in aviation because it connects directly to the atmospheric pressure at sea level, which is critical for accurate altitude readings. When pilots adjust their altimeters before flight or during landing, they refer to the altimeter setting to ensure their altitude reflect accurate position relative to the terrain and air traffic.

In aviation, the standard atmospheric pressure at sea level is often given as 29.92 inches of mercury (inHg), making this measurement convenient for pilots who are operating within the United States. The use of inches of mercury has historical significance, and its prevalence in aviation is rooted in the traditional practices established over many years, which continue to be relevant today.

While it is true that other units like hectopascals and millibars are used for meteorological measurements, they are more common in weather reports and not specifically for altimeter settings in aviation contexts. Centimeters of mercury is another unit of measurement for atmospheric pressure but is less common in aviation practice. Therefore, the focus on inches of mercury for altimeter settings aligns with aviation standards and ensures consistent communication and understanding among pilots and air traffic controllers.