Mercator vs Robinson: what's the difference?
The Mercator projection keeps angles true but greatly enlarges areas far from the equator. Robinson keeps nothing perfectly, yet it holds every distortion within moderate limits so the world looks natural. Greenland covers 105% of Africa's area on Mercator, 13.5% on Robinson, and 7.1% in reality.
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| Feature | Mercator | Robinson |
|---|---|---|
| Basics | ||
| Distortion class | Conformal | Compromise |
| Graticule type | Cylindrical | Pseudocylindrical |
| Creator | Gerardus Mercator | Arthur H. Robinson |
| Year | 1569 | 1963 |
| What it looks like | Meridians and parallels form a rectangular grid, and the spacing between parallels grows toward the poles, so polar regions are hugely enlarged. | Parallels are straight lines, meridians are gentle curves, and the poles are lines about half as long as the equator. |
| Distortion | ||
| Area | Distorted | Compromise |
| Shape | Preserved | Compromise |
| Distances | Distorted | Compromise |
| Angles and directions | Preserved | Compromise |
| Continuity | Preserved | Preserved |
| By the numbers | ||
| Greenland on the map, as a share of Africa | 105%15× too large | 13.5%1.9× too large |
| Average angular distortion over land | 0°None, the map is conformal | 23° |
| Practical traits | ||
| Map outline | Rectangle | Rectangle with rounded sides |
| Rhumb lines (constant bearing) drawn straight | Yes | No |
| Great circles (shortest routes) drawn straight | No | No |
| A pole at the centre of the map | No | No |
| Where the map is cut | Nowhere, the map is continuous | Nowhere, the map is continuous |
| All oceans in one piece | No | No |
| Use | ||
| Typical uses | Marine navigation, aviation, and most modern web mapping applications (Web Mercator, used by Google Maps, OpenStreetMap). Unsuitable for general educational wall maps due to extreme scale distortion. | Wall maps, educational atlases, and general geographical publications. It was the primary map projection used by the National Geographic Society from 1988 to 1998. |
| First choice for | None of the jobs we describe | |
| A good alternative for | None of the jobs we describe | |
| Not recommended for | None of the jobs we describe | |
The “By the numbers” rows are measured when the site is built, on the same maps the lab draws, over a grid of points every half degree (every 2° for all land). The true areas of Greenland and Africa come from our country and continent profiles.
The key differences
- The trade-off: Mercator gives up area to keep angles true. Robinson keeps neither angles nor area perfectly, but it does not badly break either.
- Country sizes: Robinson also enlarges the polar regions, but far less. Greenland covers 13.5% of Africa's area on it and 105% on Mercator.
- Shapes: the average angular distortion over land is 0° on Mercator and 23° on Robinson. Countries near the edges of a Robinson map lean slightly.
- Poles: Mercator cannot show the poles, which lie at infinity, so the map is usually cut off at high latitudes, well short of the poles. Robinson shows the whole world and draws the poles as lines.
- Construction: Mercator follows from a mathematical formula. Robinson adjusted coordinates in a table until the map looked right, and points between the table values are found by interpolation.
A sailor's map and a wall map
Mercator published his map in 1569 with navigation in mind: a course drawn on it with a ruler keeps a constant compass bearing. Over the centuries, though, it also went up on classroom walls, where it fixed the image of a huge Greenland and a small Africa.
Arthur H. Robinson designed his projection in 1963 for the publisher Rand McNally. The aim was a world map that simply looks right. National Geographic used it as its main world map from 1988 to 1998.
Read more
Frequently asked questions
No. Robinson is not equal-area and also enlarges areas far from the equator, although much less than Mercator: Greenland covers 13.5% of Africa's area on it instead of 7.1%. True proportions need an equal-area map such as Equal Earth.
Robinson shows the proportions of the continents far better than Mercator, so it works better on a wall. If the lesson is about the size of countries, an equal-area map is better still.
In 1998 National Geographic replaced Robinson with the Winkel Tripel projection. Both are compromise projections, and we compare the two on a separate page.
Other comparisons
Each of these pairs has its own page that explains the differences, gives the historical context and answers common questions.