True size comparer

Web maps make Greenland look as big as Africa; it is a fourteenth the size. Pick countries and drag them across the map: the shape changes as it moves, so what you see is the true size.

How to use it

  1. Choose a country and press Add.
  2. Drag the shape across the map. It shrinks towards the equator and grows towards the poles.
  3. Add more countries to compare them. Read the real areas in the table.

5 practical uses

  1. Show a class the distortion of the Mercator map.
  2. Compare the real size of countries for an article or a slide.
  3. Settle how big Greenland, Australia or Alaska really is.
  4. Judge the scale of a country you are about to travel across.
  5. Illustrate a post about map projections.

The maths behind it

The Mercator projection scales the map by the secant of the latitude, sec φ = 1/cos φ, so at 60° everything is drawn twice as large and at 80° nearly six times. To move a country, each vertex is stored as its bearing and great-circle distance from the country's centroid, and re-placed from the new centroid with the direct geodesic formula, which keeps the true size and shape to within the change in convergence of the meridians.

Why maps lie about size

The Mercator projection, which every web map uses, keeps angles right (so north is always up and a compass course is a straight line) at the cost of size: scale grows with the secant of the latitude, so at 60° everything is twice as wide and twice as tall as at the equator, four times the area. Greenland at 72°N looks the size of Africa; in truth Africa is 14 times larger. This tool moves each vertex of the shape by its bearing and distance from the shape's centre, which keeps the true size and near enough the true shape.

More tools

Map makersPin map makerDrop pins with labels, colour them, and export the map as an image or a file. Map makersMap drawerDraw points, lines and shapes on the map, then save them as GeoJSON, KML or an image. Map makersLegend makerBuild a map legend with your own colours and labels, and download it as an image. Map makersRegion painterClick countries or US states to colour them, for a visited map or any other. Where am IWhat city am I in?Find the city, town or village you are in, and the nearest larger cities. Measure and routeMap radiusDraw a circle of any radius around a point and see what falls inside it. Measure and routeDetour calculatorHow much a stop on the way adds to a drive, in distance and in time. CoordinatesGeohash converterTurn coordinates into a geohash and back, with the cell drawn on the map. Waymorphic MapAll 64 toolsWhere am I, measuring, coordinates, map makers, lookups, sun and moon, the lines of the globe.

Questions and answers

Why does Greenland look as big as Africa on maps?

Web maps use the Mercator projection, which stretches the poles. At 60 degrees of latitude everything is drawn twice as wide and twice as tall as at the equator. Africa is fourteen times the size of Greenland.

How is the shape re-projected?

Each corner is moved by its bearing and distance from the shape's centre, so the true size and nearly the true shape are kept wherever it is.

Why do the areas differ from the official figures?

They come from the Natural Earth outlines, which include lakes and simplify coasts.

Embed this tool on your website

Paste this code where the tool should appear. It shows the tool alone, without this page's text, and links back here. It is free to use; the map data credit stays on the map.

<iframe src="https://waymorphic.com/tools/true-size-comparer?embed=1" width="100%" height="760" style="border:0;border-radius:12px;max-width:100%" loading="lazy" allow="geolocation; fullscreen; clipboard-write" title="True size comparer – Waymorphic Map"></iframe>

Change height to suit your page. To open the tool with a place already set, add the settings from this page's address bar (the part after #) to the end of the src. The embedded tool asks the visitor's browser for their location only when they press the button, and the allow attribute lets that work inside the frame.