Map Data, Area Calculations and Coverage
Our answers compare approximate mapped areas. They are not official land-area or total-area rankings.
Where the maps come from
We use the public-domain Natural Earth dataset, pinned to version 5.1.2. The world game uses 1:50 million country boundaries. Regional games use 1:10 million first-level administrative boundaries.
Areas are calculated from the original polygons before the display paths are simplified. Source URLs and SHA-256 file hashes are available in the original data record and cross-level data record. These are fixed source files, not live official boundary updates.
What counts as area?
We calculate the spherical footprint inside each source polygon, using a mean Earth radius of 6,371.0088 km. Lakes, islands, coastlines and overseas groupings follow those polygons. Empty space between separate islands does not add to their area.
Official tables may count land, inland water and overseas territories differently. That can matter for close comparisons. Use the figures here to understand the game’s maps, not as a substitute for a national statistical source.
Why the shapes change size
Each place is drawn in a locally centred azimuthal equal-area projection. Before your choice, the shapes fit their cards independently. After it, their filled display areas are normalised to a common scale.
Linear scaling uses the square root of the area ratio. For two otherwise identical shapes, four times the area means twice the width, not four times the width. Narrow and compact outlines are normalised by their filled areas rather than their bounding boxes.
Coverage of each game
The world set includes 181 countries and selected territories with mapped areas of at least 2,000 km². Antarctica and smaller places are excluded. It is not a complete list of sovereign states; Greenland, for example, appears as a territory.
- United States: 50 states, without DC or US territories.
- Canada: ten provinces and three territories.
- Australia: six states, Northern Territory and Australian Capital Territory. External territories and Jervis Bay are excluded. Lord Howe Island is grouped with New South Wales; separately mapped Macquarie Island is not included.
- Brazil: 26 states and the Federal District.
- China: 31 mainland provincial-level regions. Hong Kong, Macao, Taiwan and separately mapped Paracel Islands are outside this limited set.
- Japan: all 47 prefectures.
Names and boundaries follow the map source and do not express a position on disputed sovereignty. See Natural Earth’s terms of use and geographic disclaimer.
Continents and Home vs the world
Continental games filter the world set using Natural Earth’s single continent assignment. Transcontinental places are not split or counted twice. Overseas pieces remain grouped with their source entry.
Home vs the world pairs one regional subdivision with one country or territory, excluding its parent country. Both sides use 1:10 million source maps. Country areas can therefore differ slightly from the less detailed world-game data. France includes French Guiana in the cross-level set; it is not a metropolitan-France-only comparison.
Precision and close answers
Generalised coastlines and a spherical Earth model limit precision. Square-kilometre labels are rounded for orientation, not surveying. Generated questions exclude pairs less than 8% apart in area. That cutoff is a game-design choice, not a measured error bound. Display pixels and outline strokes can also introduce small visual differences.
Reproducible questions, local scores
Daily questions use the UTC date, game ID and a versioned generator. Current rounds use version 2; older version 1 links and already-started daily rounds remain supported. Shared links preserve an exact pair, a question sequence or an older challenge seed.
The world daily spreads questions across continents and reduces repeated places within a round. It does not guarantee that a pair will never return on another day. Scores stay on the device and are not verified by a server.