How the maps and numbers are made

Geographic model

Area is calculated from prepared polygon geometry on a sphere of radius 6,371 km. The method identifier is sphere-r6371-v1. D3’s spherical area calculation returns steradians, which are multiplied by the square of that radius to obtain square kilometres. Holes and separate polygon parts are retained where the source geometry supplies them.

Numbers shown here are boundary-model area estimates. They are not official land-area statistics and do not promise the inclusion or exclusion of every inland water feature under a national statistical definition. Ratios use unrounded stored values; displayed areas are rounded for reading.

The project fixes its boundary release at Natural Earth 5.1.2. Its prepared data identifier is ne-5.1.2-lab-1, and its scope policy identifier is ne-regions-islands-v1. These identifiers make a result traceable to a particular preparation. They do not imply that the map is an up-to-the-minute official boundary record.

Country and continent scope

Comparison place	Included	Excluded or qualified
United States	The 50 states and District of Columbia, including Alaska and Hawaii	Puerto Rico and other separately mapped territories
Metropolitan France	The European mainland and Corsica	Overseas regions and territories
Spain	Mainland and mapped island parts, including the Balearic and Canary Islands	Scope follows the prepared source geometry
United Kingdom	Great Britain and Northern Ireland with mapped associated islands	Crown Dependencies and overseas territories
Europe	The Natural Earth physical region and its assigned island masks	Greenland and Cyprus; transcontinental countries are geographically partitioned
Africa	The Natural Earth physical region and its assigned island masks, including Madagascar	Sinai is outside the mainland mask; generalized coastlines can omit slivers

Country and territory labels in the picker identify selectable map objects. The continent grouping is a navigation aid; it is not the algorithm used to calculate continental area. In particular, Europe’s area is not the sum of whole countries selected by a continent label.

For continental geometry, the preparation unions the source’s physical continent, island and island-group masks, then intersects that mask with the versioned land geometry. The planar clipping step assembles the scope; the resulting polygons are then measured on the sphere. The complete mask list is retained in the project’s scope manifest. Generalized masks may leave narrow coastal discrepancies, so these results should not be treated as survey-grade continental partitions.

Boundaries and names

The site’s boundary dataset includes Taiwan, Hong Kong and Macao within China. Other coastlines, boundary features and place names follow the prepared source release and documented project corrections. Natural Earth explains that map boundaries involve cartographic choices. This project does not present a simplified world outline as a legal boundary determination.

Labels are selected for readability. A country label and a capital marker are different features: the marker uses a source-backed capital position when one is available. A missing label on a world view does not mean that the country or island is absent from the geographic data. Use the picker to locate small places.

Detail levels and physical relief

The coarser world outlines are simplified from the same prepared boundary geometry. They preserve shared topology but can lose small rings. The complete prepared entity geometry supplies the comparison calculations. A display-level change never replaces a stored area figure with an estimate from screen pixels.

Natural Earth’s 1:10 million category is a generalized cartographic scale, not ten-metre imagery. More zoom reveals more of the available detail; it cannot recover features missing from the source.

Physical relief uses Natural Earth I 3.2.0 land-cover, shaded-relief and water imagery. It is served as fixed raster tiles and reprojected to the selected map. The styling adjusts contrast and saturation for reading beneath the boundary overlay. It is neither live satellite imagery nor a measurement-grade elevation model.

Projection and comparison rules

The same three adapters are used across the site: Equal Earth, Robinson and Mercator. Mercator views stop at approximately 85.05° north and south because the poles have no finite Mercator coordinate. Equal Earth preserves area but changes shapes and angles; Robinson makes a compromise without either exact preservation property.

The home map’s movable copy uses a rigid rotation on the sphere, followed by reprojection. It is not moved by adding independent longitude and latitude offsets, and it is not resized to match a desired screen result. Its geographic area stays fixed. At the map’s cut, the projected outline can split into multiple pieces.

Selected article comparisons use a common Equal Earth scale for the two silhouettes. By contrast, the map maker’s two-world composition fits each projection independently. Those two display arrangements answer different visual questions.

Reproducing or questioning a result

The source preparation records file hashes, dataset versions and scope definitions. Downloads list a SHA-256 digest and dimensions. Automated checks exercise spherical area, projection inverses, island scope and rigid movement; the release report distinguishes those checks from manual or external review.

For a disagreement, first compare the scope and area definition. The area-methods guide gives examples. Report a specific page, place and supporting source through Corrections, especially if a source feature or prepared scope appears to be missing.