How we measure

Outlines

The 246 places come from Natural Earth, 1:10m Admin 0 - Countries (public domain). Natural Earth draws the boundaries as they are on the ground today (its “de facto” boundaries), at a scale of 1:10 million.

Areas

Each area is measured on the WGS84 ellipsoid with GeographicLib, from the full-detail outline. A sphere would be off by up to half a percent; the ellipsoid is not. Long straight edges in the source are first split along the parallel or meridian they were drawn on, so they are not cut short by the great-circle between their ends.

The outlines drawn on the pages are simplified so they load quickly. Simplifying never changes a measured area, because areas are computed before drawing.

Measured areas are shown rounded, because the outlines themselves are only that precise. Official figures usually include inland water and use national definitions, so they can differ from ours.

Main territory

Many countries own land far from home: French Guiana is part of France, Hawaii is part of the United States. A comparison of “France” usually means the part of it that fits on a regional map, so each place has a main territory: its largest landmass plus every part within 1,000 km of that landmass or of a part already included. Everything else is overseas territory.

Comparisons and drawn outlines use the main territory. Place pages also give the area with overseas territory, and say how much is left out.

Drawing at true scale

Each outline is projected with a Lambert azimuthal equal-area projection centred on its own centroid, in kilometres. Equal-area means every region of the drawing has its true area, and projecting each place around its own centre keeps its shape as faithful as a flat drawing allows. Two places are then laid over each other at the same scale with their centres together, so they are never stretched the way a single world map stretches high latitudes.

Population

Population figures are Natural Earth’s estimates, with the year shown on each page, and cover the whole country, overseas territory included. Density divides that by the area with overseas territory, so both numbers describe the same land.

Provinces, states and union territories

The provinces of China, the states of the United States and the states and union territories of India come from Natural Earth’s 1:10m Admin 1 file (public domain), measured exactly as countries are, and each region’s whole area is counted, every island included. The regions of a country add up to that country’s measured area, to within 0.1%. Official area, population and capital come from Wikidata (CC0); for China the population is the 2020 census headline (“permanent population”), for the United States the 2020 census, and for India the 2011 census, the newest headline figure Wikidata holds for most of its units (three carry a different year, shown wherever the figure is). Where Wikidata gives a different type from Natural Earth (Himachal Pradesh is a state, not a union territory), the page follows Wikidata.

Each region is matched to the countries closest to it in area and in population. A match is a plain comparison of two published figures. Places whose status is contested, dependencies, and places that Natural Earth draws as separate entries of a country with regions (Hong Kong, Macau and Taiwan for China) are never used as automatic matches. A region under 2,500 km² is matched against the small countries and island nations instead, and the closest region of each other country with regional pages is matched as well. Any pair can still be compared by hand; the regions of the three countries are on one page, side by side.

The first-level divisions of Germany, France, Italy, Spain, Japan, Brazil, Canada, Australia, Mexico and Thailand are made the same way. Where Natural Earth’s file draws the tier below (the departments of France, the provinces of Italy and Spain), those pieces are joined along their shared borders into the regions, and each joined outline is measured whole. A unit under 5,000 km² whose outline is more than 25% away from the official area, and which Natural Earth draws from a handful of points (Ceuta and Melilla), shows the official area. Islands that Natural Earth draws under the wrong prefecture (the Amami Islands) are moved to the right one. Each country’s page says which census year its populations come from.

Rights

Source data and images retain their respective rights. The outlines come from Natural Earth (public domain) and the official figures from Wikidata (CC0); each source is named where it is used. The site’s own drawings, share cards and text are © 2026 Slow Signal Labs.

Lakes and seas

Lakes, reservoirs, seas, gulfs and bays come from three Natural Earth physical files (lakes and reservoirs, marine areas, and island outlines), all public domain. Natural Earth draws marine areas for labels, not as a survey: it cuts the Mediterranean into its named sub-seas and splits the Atlantic and the Pacific at the equator. So no outline is taken on trust. Each one is measured on the ellipsoid and compared with the area Wikidata (CC0) publishes for the same water body. Within 2% it agrees, within 5% it is near and is matched to countries by rule, within 10% it keeps a page and is flagged; beyond that, or with no published area to check against, it is left out. Of 1621 lake and marine outlines, 260 passed.

Where Natural Earth draws one sea or one lake system in several pieces, the pieces are listed in config/waters.json and counted together only if their sum agrees with the published area of the whole (the Mediterranean with its named marginal seas, the Baltic Sea with its gulfs, the Gulf of Mexico with the Bay of Campeche, the Great Lakes). A lake outline that lies mostly inside a larger lake, such as Georgian Bay in Lake Huron, is counted once, in the larger one. The oceans are not drawn: no ocean outline agrees with its published area.

A lake or a sea has no legal boundary, so the outlines are cartographic and every page shows the measured area beside the published one. The countries listed on a shore are those whose Natural Earth outline contains the water or lies close to it; that is geometry, not a statement about who owns the water. Names that are disputed carry one neutral sentence, the title is Natural Earth’s name, and every other name shown has its source named.

Disputed boundaries

Where a boundary or a political status is contested, the page says so in one sentence and draws Natural Earth’s de facto outline. Size Versus takes no position, and the outline does not change with the reader’s language or country.