How do we measure OpenStreetMap’s data coverage? One approach is to compare it against established references like the CIA World Factbook. As a US Government work, the Factbook is publicly available and freely licensed, and it contains measurements of paved & unpaved road lengths in every country in the world.

We downloaded the Factbook’s road length numbers and compared them against OpenStreetMap’s road data using Tile Reduce and OSM QA Tiles. We found for the United States about 6.2 million miles of motor roads and 7.1 million miles of any type of road or path. OpenStreetMap performed well across all the continents, but still needs work in places like India and China.

One caveat is that the Factbook doesn’t clearly define what constitutes a road, so we’ve provided numbers for both roads in general and only those fit for motor vehicle traffic.

Country overview page

Country metrics page showing OpenStreetMap coverage.

Check out the metrics below. Tim and I would love to talk more about measuring OpenStreetMap coverage on twitter, or in person today at Geography 2050.

Country OpenStreetMap
all roads and paths
motor roads only
CIA factbook
Afghanistan 67,845 25,400 26,191
Argentina 389,569 370,007 143,769
Australia 631,146 487,207 511,523
China 977,075 935,100 2,551,590
Egypt 61,943 55,397 85,395
Germany 1,341,791 554,803 400,784
Indonesia 181,731 169,230 308,577
Japan 976,655 828,283 756,288
Kenya 58,628 47,813 99,965
Mexico 335,719 308,266 234,667
South Africa 233,758 207,005 464,173
Thailand 193,083 164,660 111,880
United Kingdom 489,640 320,376 245,086
United States 7,147,209 6,220,189 4,092,728

All comparisons on a zoom level 12 tile basis where one tile is either counted fully for a country or not. This leads to a margin of error that is negligible for large countries but can be significant for smaller countries.

View our searchable metrics page, or browse the full list.