Guess the Real Size is a free map game: you see two countries drawn at the same scale as on a Mercator map (the projection behind most web and classroom maps), guess how many times bigger one really is, then watch both morph into the area-true Equal Earth projection to see how close you were. Each round scores 0–100 points, ten rounds make a game, and the same Daily challenge is shared by everyone, with an Endless practice mode, streaks and a share card. It shows why Greenland looks bigger than DR Congo on a Mercator map even though it's smaller.
Why countries look the wrong size on maps
Mercator preserves local angles, which helps navigation, but inflates area by about sec²(latitude): ×2 at 45°, ×4 at 60°, and ×8.5 at 70°. Greenland can look larger than DR Congo even though its real area is smaller. Equal Earth keeps relative area true while changing shapes.
On September 4, 2026 the UN General Assembly adopted the non-binding resolution “Correct the map” by 164 votes to 1, with 6 abstentions. It encourages governments, schools and tech companies to use equal-area projections such as Equal Earth when the relative size of continents matters; it doesn't ban Mercator (UN press release).
Biggest Mercator illusions in the game
Ratios below are the first country's area divided by the second's. Apparent ratios use the displayed Mercator polygons; true ratios use unsimplified boundaries.
| Pair | Mercator apparent ratio | True ratio |
|---|---|---|
| Greenland / DR Congo | 14.96× | 0.92× |
| Canada / Brazil | 5.14× | 1.16× |
| Russia / China | 5.31× | 1.80× |
| United Kingdom / Madagascar | 1.01× | 0.40× |
| Norway / Japan | 3.09× | 0.87× |
How scoring works
Each round awards 0–100 points. The error is |ln(guess ÷ true ratio)|, so guessing twice as large and half as large have the same penalty. Within a factor of 1.10 earns 100; a factor of 4 or more earns 0. Between those limits points fall linearly with log error, rounded to the nearest integer. Percentage off is (exp(log error) − 1) × 100. Ten rounds total 1000 points. Green squares mean 75–100, yellow 35–74, red 0–34.
The logarithmic slider covers 1/30× to 30×; pairs stay within that range. Daily pairs are seeded by the UTC date. Practice mixes new pairs, with extra weight for projection surprises and no country repeated within a game. Streaks count consecutive completed UTC daily challenges on this device; best score includes both modes.
Data and attribution
Made with Natural Earth Admin 0 – Countries, 1:50m (public domain). Areas are computed from unsimplified boundaries on the authalic sphere (R = 6,371,007.2 m), then shown approximately to three significant figures. Official figures can differ by a few percent (lakes, coastline detail, disputed areas). Outlines are simplified with Visvalingam weighting; small islands may be omitted. France is metropolitan only; Norway is mainland only. Greenland follows Natural Earth's country-level classification. Boundary display does not imply a position on sovereignty.
Mercator uses x = λ and y = ln(tan(π/4 + φ/2)), with latitude clamped at ±85°. Equal Earth uses the formulas and constants of Šavrič, Patterson & Jenny (2018), The Equal Earth map projection. Both countries share a scale in each projection. Screen positions interpolate for 900 ms; reduced motion switches instantly. Shapes are not independently resized.
How to play
- Look at the two outlines. They're drawn exactly as a Mercator map shows them, at one shared scale.
- Drag the slider (or use ← and →) to say how many times bigger country A really is than country B, from 1/30× to 30×.
- Press Lock in. The shapes morph to the Equal Earth projection, which keeps true area, and you see both real areas in km² and mi².
- Score up to 100 points per round: within 10% of the true ratio is a perfect 100. Ten rounds make a game, up to 1,000.
Play the Daily challenge (the same 10 pairs for everyone, new at midnight UTC, one try) or Endless practice with random pairs. Share your result as emoji squares or a 1200×630 image.
Why do countries look the wrong size?
The Mercator projection keeps angles and coastline shapes correct, which made it the standard for navigation, but it stretches area more and more away from the equator: about 2× at 45° latitude, 4× at 60° and 8.5× at 70°. That's why Greenland, Canada and Russia look enormous while Africa, South America and India look small. Equal-area projections such as Equal Earth fix area at the cost of some shape distortion.
| Pair | Looks like on Mercator | Real area ratio |
|---|---|---|
| Greenland vs DR Congo | Greenland ~15× bigger | Greenland is smaller (0.92×) |
| Canada vs Brazil | Canada ~5× bigger | Canada only 1.16× bigger |
| United Kingdom vs Madagascar | about the same | UK is 0.4× the size |
| Norway vs Japan | Norway ~3× bigger | Norway is smaller (0.87×) |
Tips for a high score
- Latitude is everything. The further a country is from the equator, the more you should shrink it in your head.
- Compare countries at similar latitudes almost as they look, but discount a high-latitude country heavily against a tropical one.
- Learn a few anchors: Russia ≈ 16.9 million km², Brazil ≈ 8.5 million, India ≈ 3.2 million, Greenland ≈ 2.2 million (our Natural Earth figures).
Data
Country outlines and areas come from Natural Earth's public-domain 1:50m boundaries (terms); the Equal Earth formulas are from Šavrič, Patterson & Jenny (2018) (paper). Areas can differ from official figures by a few percent (lakes, coastline detail, disputed areas). France is metropolitan only and Norway mainland only.
Frequently asked questions
What is the Guess the Real Size game?
A free browser game: two countries are drawn as they appear on a Mercator map, you guess how many times bigger one really is, and the map morphs to the area-true Equal Earth projection to reveal the answer.
Is Greenland really as big as Africa?
No. On a Mercator map Greenland looks about as big as Africa, but Africa is roughly 14 times larger. Greenland is even a bit smaller than DR Congo.
Why does the Mercator map distort size?
Mercator keeps angles correct for navigation, so it stretches areas away from the equator: about 2× at 45°, 4× at 60° and 8.5× at 70° latitude.
What is the Equal Earth projection?
An equal-area world map projection published in 2018 by Šavrič, Patterson and Jenny. Every country keeps its true relative size, so it's used here to reveal the answer.
How is the score calculated?
Each round scores 0–100 based on how far your guessed ratio is from the true one on a log scale: within 10% earns 100, off by 4× or more earns 0. Ten rounds total up to 1,000.
Is there a daily challenge?
Yes. The Daily has the same 10 country pairs for everyone, changes at midnight UTC and can be played once. Endless practice has unlimited random pairs.
Why isn't the United States in the game?
Its outline would need Alaska and Hawaii drawn far from the mainland, which doesn't work in a side-by-side comparison, so it's left out for now.