Height above sea level


Height above mean sea level is a measure of the vertical distance of a location in reference to a historic mean sea level taken as a vertical datum. The combination of unit of measurement and the physical quantity is called metres above mean sea level in the metric system, while in United States customary and imperial units it would be called feet above mean sea level.
Mean sea levels are affected by climate change and other factors and change over time. For this and other reasons, recorded measurements of elevation above sea level might differ from the actual elevation of a given location over sea level at a given moment.

Uses

Metres above sea level is the standard measurement of the elevation or altitude of:
The elevation or altitude in metres above sea level of a location, object, or point can be determined in a number of ways. The most common include:
Accurate measurement of historical mean sea levels is complex. Land mass subsidence can give the appearance of rising sea levels. Conversely, markings on land masses that are uplifted due to geological processes can suggest a lowering of mean sea level.

Other measurement systems

above sea level is the most common analogue for metres above sea level in the US customary measurement system, abbreviated FAMSL.

Abbreviations

Often, just the abbreviation MSL is used, e.g. 8848 m MSL. Metres above sea level is commonly abbreviated mamsl or MAMSL, based on the abbreviation AMSL for "above mean sea level". Other abbreviations are m.a.s.l. and MASL.