|Distance (i.e. extent; length from start to finish) of a route given in kilometers, or distance along a route marked by milestone.|
|Used on these elements|
|Status: in use|
|Tools for this tag|
This describes the distance (i.e., total length; physical extent) of a geographic feature. It is used in two kinds of elements: route relations and milestone nodes, as specified below.
If no unit is given explicitly, the value is assumed to be in kilometers. If another unit is given, it should be separated from the number by a space. Any decimal should be specified using a dot (.) as the decimal separator. Abbreviations for other units are described on the Units page.
When used on a route relation, distance describes the total distance of the route. It should not be used on single ways, because it will cause confusion if the way is split and the tag is kept.
For example, the total length (physical extent) of the Polish Autostrada A1 is currently 326 km, so the relation for distance=326.is tagged
((Q: This definition still leaves certain issues undetermined. Lots of roads have breaks or jumps where they are not defined. They disappear at these gaps and then reappear elsewhere. How does the "distance" of a relation handle these gaps? Is the distance of that gap included or ignored? -- A: If the route contains branches and a meaningful distance is not automatically computable, "distance" should be manually filled with something sensible. If the route is incomplete in OSM, "distance" can be filled with e.g. the officially declared length. (The Waymarkedtrails service shows the "distance" value with a "official length" label.)))