Relative scale
There have existed two traditions parallelly in the units of measurement, thus also in the map scales on the territory of Estonia:
- scales based on the system of measures of Old Livonia (5200; 10400; 52000), the cubit (61 cm);
- scales based on the Russian system of measures (4200, 5600, 8400, 10500, 42000), the verst and inch. It was calculated, how many inches (2,54 cm) on a map are equal to one verst (1066,8 m) or 500 fathoms (in German Faden) in reality. On a map with the scale 4200, one verst in reality corresponds to 10 inches on the map, on a map with the scale 5600 – 7,5 inches. On large scale maps, fathom was used as the main unit of measurement.
The Russian system of measures began to spread during the second half of the 19th century. All maps of the Swedish era are in the system of measures of Old Livonia.
If a relative scale is missing on a map, it has been transformed either from the graphic or lexical scale. When both the lexical scale and relative scale are missing on a map, an estimated scale is given in square brackets, e.g. [4200].