Linear measurement of an irregular coastline (the rocky coast of the Provence Alpes - Côte d’Azur region, the west coast of Corsica or the western end of the coast of Roussillon) gives very different results according to the scale of the maps used. The data presented in MEDAM are standardised: they were all obtained by measurements (same method) on maps of the same scale: 1/10 000. The data available elsewhere (sometimes appreciably different) refer, depending on the region, to maps of different and / or smaller scales (many measurements were made on 1/25 000 scale maps), but most often the scale of the maps used is not specified.

The coastline measured is the natural (original) coastline prior to any reclamation from the sea. In the case of constructions on reclaimed areas (harbours, landfills, etc.), we have attempted to trace the outline of the original coastline. This outline was based on examination of either aerial photographs (for constructions dating from the last century), or on very early maps (as for the roadstead of Toulon, the coastline of the harbour at Marseille or the harbour at Nice). The outline of the coast adopted can be seen in the cartographical data.

The list of early maps used is available (see list of early maps).

Several particular cases related especially to redevelopments partly constructed by excavating the land, superimposed constructions and urban or rural district borders that overlap a reclamation area are cited for each reclamation concerned in the descriptions of reclamation (under the heading ‘Comments’ in each descriptive note).

Measurements were made on a large number of maps.

The total length of coastline for the whole of the French Mediterranean coast is 2 057 km, 5 km for the coast of Monaco and 100 km for the coastline of the Etang de Berre (or 2 162 km for the whole coastline included in MEDAM).

The total length of the continental French coastline (including Monaco) is 1 085 km including 853 km for the coast of Provence-Alpes-Côte d’Azur (not including Monaco and Berre) and 227 km for the coast of Languedoc Roussillon. The length of the coast of Corsica is: 977 km.
Details by county (département ), by urban or rural district (commune) and by ECD water mass are available in  the numerical data.