Where do RealSize.World numbers come from?

Three different concepts, three separate metrics

US states: Texas, Alaska and California

State areas come from the Census Bureau table for boundaries as of January 1, 2010. Total and land areas are shown separately. Census water area includes inland, Great Lakes, coastal and territorial waters. National statistical definitions can differ, so each subject has its own source and reference period.

• Texas: 695,662 km² total, 676,587 km² land (2010).
• Alaska: 1,723,337 km² total, 1,477,953 km² land (2010).
• California: 423,967 km² total, 403,466 km² land (2010).

USA comparisons include all 50 states and Washington, DC, including Alaska and Hawaii. Lower 48 means the 48 contiguous states and is not used as a substitute for the whole USA.

Outlines and boundaries

Outlines come from Natural Earth through world-atlas. The app uses 1:50m and 1:110m scales, so geometry is simplified for visualization and is not suitable for geodetic measurement. Natural Earth displays de facto boundaries by default. Names and boundaries do not express a RealSize.World position on territorial disputes.

New state and Europe outlines use Natural Earth 5.1.1 directly at 1:50m scale. Alaska includes the Aleutians on both sides of 180° longitude. France comparisons cover metropolitan France and Corsica, excluding overseas territories. Europe includes European Russia, Great Britain, Ireland and Iceland. Its approximate 10,180,000 km² area is an editorial continental estimate, not the area of the European Union. The conventional division between Europe and Asia follows Natural Earth's physical regions layer.

Natural Earth releases its data in the public domain and permits modification and commercial use. State figures are attributed to the Census Bureau; we do not reproduce its photographs or graphic material.

Natural Earth · terms of use ↗ · Census Bureau · data citation ↗ · Geographic file provenance and versions ↗

Antipodes and the Earth's interior

The “Dig through the Earth” tool checks whether an antipode falls on land using the Natural Earth 1:50m map. To find the nearest land it adds small islands from the 1:10m map (world-atlas 2.0.2) that the 1:50m map lacks, with about a dozen outline points per island. Ocean and sea names come from the water areas used in the quizzes. Distances follow great circles on a sphere with a radius of 6,371 km and are rounded to 10 km.

We calculate the fall time, speed and pressure ourselves from the PREM density model (A. M. Dziewonski, D. L. Anderson, Preliminary Reference Earth Model, Physics of the Earth and Planetary Interiors 25, 1981): gravity from the mass inside each shell, pressure from the weight of the rock above and the motion of a body falling without air resistance. The model reproduces the Earth's mass, surface gravity and central pressure, and the fall time matches the paper by A. R. Klotz (American Journal of Physics 83, 2015). Tunnel length and the plumb-line offset use the WGS 84 ellipsoid. We do not give interior temperatures as numbers. The approximate starting point comes from the device time zone: the coordinates of each zone's principal city come from the IANA time zone database, release 2025b (zone.tab, zone1970.tab and backward, public domain).

A. R. Klotz · The Gravity Tunnel in a Non-Uniform Earth ↗

Data licences and citation

We use data from external sources under their licences. Citations follow the format requested by each data provider.

• The World Bank: World Development Indicators: Population, total (SP.POP.TOTL). Data source: UN Population Division, national statistical offices, Eurostat, UN Statistics Division. Licence: CC BY 4.0 ↗
• The World Bank: World Development Indicators: Land area (AG.LND.TOTL.K2), Surface area (AG.SRF.TOTL.K2). Data source: Food and Agriculture Organization of the United Nations (FAO). Licence: CC BY 4.0 ↗
• United Nations Statistics Division: Demographic Yearbook 2024, Table 3 (total surface area).
• Flags: Flagpedia.net ↗, public domain. We downloaded the files once and serve them from our own server.

Our changes: for each country we use the latest year available in the source. We calculate population density ourselves as population divided by land area and round the result. When the UN gives no total surface area, or gives a value smaller than the land area, we use the World Bank total surface area instead. Rankings, comparisons and quizzes are calculated from these data. The data providers are not responsible for these changes and do not endorse RealSize.World.

How calculations and comparisons work

• Size comparisons use total surface area, not area calculated from simplified SVG geometry.
• The 1:1 overlay uses a locally centered azimuthal equal-area projection at a shared scale. It preserves geometric area ratios, which need not equal statistical total-area ratios: coastal outlines omit some waters and are simplified.
• The Mercator verdict is an estimate using 1/cos²(φ) at each outline's centroid latitude. It does not measure the entire projected area.
• Population density is calculated as population divided by land area when both metrics are available.
• Population and area reference periods may differ; they are displayed separately.
• A missing observation is not replaced with zero or an average.

Current snapshot coverage

Updates and quality control

Data is fetched by a controlled importer during editorial updates, stored in the repository, and validated before publication. The site does not fetch numbers live on every visit. This makes builds reproducible and prevents an external API outage from changing page content.

The importer stops on an invalid source response. Validation checks codes, values, sources, and the relationship between total and land area. Exceptional cases are flagged for a manual decision.