Montana and Caspian Sea are almost exactly the same size

Montana (state) covers about 379,000 km² (147,000 mi²) and the Caspian Sea (sea) about 379,000 km² (146,000 mi²). Their outlines are laid over each other below at one scale. The Caspian Sea outline is Natural Earth’s, checked against the published area.

379,000km²Montana
379,000km²Caspian Sea

200 km

Montana
Caspian Sea

Caspian Sea: Whether the Caspian is called a sea or a lake depends on the definition used. Its name says sea and Natural Earth draws it with its marine areas, so Size Versus lists it with the seas, and also shows where it would stand among the lakes.

What fits

Caspian Sea is 100% of the size of Montana.
The measured areas differ by 192 km², less than half a percent: closer than the measurement itself is certain.
Measured in Belgiums: Montana is about 12.4, Caspian Sea about 12.4.

How they differ

Their centres are about 9,960 km apart.
A standard web map misstates the comparison: Montana at 47°N is drawn about 2.2× too large and Caspian Sea at 42°N about 1.8×, so the map shows Montana as 1.20× the size of Caspian Sea instead of 1.00×.
Together Montana and Caspian Sea cover 759,000 km², close to the size of Zambia (752,000 km², 0.9% smaller).
Montana's centre is 5.4° of latitude, about 600 km, farther north than Caspian Sea's.
Montana is a state of the United States; it is not drawn with its waters removed, and its measured area is the Natural Earth outline's.
The Caspian Sea is a sea and ranks 15th of the 42 seas on sizeversus by area.
Laid out flat, Montana stretches about 527 km north to south and 916 km east to west; the Caspian Sea about 1,170 km by 611 km.
Poured over Montana, the 78,700 km³ that Wikidata records for the Caspian Sea would stand 207 m deep.
Wikidata’s published figure of 386,000 km² agrees with our measured 379,000 km², to within 2%.

Who wins on what

Measure	Winner	By
Larger area	Montana	1.00×
Farther north	Montana	5.4° of latitude
Stretched more on a web map	Montana	2.2× against 1.8×

Both against the same yardsticks

Yardstick	Montana	Caspian Sea
Belgium 30,700 km²	12.4×	12.4×
United Kingdom 244,000 km²	1.56×	1.56×
Germany 358,000 km²	1.06×	1.06×
Japan 374,000 km²	1.02×	1.02×
France 548,000 km²	0.69×	0.69×
India 3,151,000 km²	0.12×	0.12×
Brazil 8,473,000 km²	0.04×	0.04×
United States 9,447,000 km²	0.04×	0.04×
Russia 16,980,000 km²	0.02×	0.02×

Each figure is the place's area divided by the yardstick's.

Side by side

	Montana	Caspian Sea
Is a	StateUnited States	Seasea on sizeversus
Area, measured	379,000 km²147,000 mi²	379,000 km²146,000 mi²
Area, published	381,000 km²Wikidata	386,000 km²Wikidata
Rank by area	–	15th of 42seas
Greatest depth	–	1,025 mWikidata
Volume	–	78,700 km³
Latitude range	44°N to 49°N	37°N to 47°N
On the shore	–	5 on the shore

Published figures: Wikidata (CC0). A lake or a sea has no legal boundary: the measured area is that of Natural Earth’s outline, and it is shown beside the published one.

Natural Earth’s outlines of Kazakhstan, Russia, Turkmenistan, Azerbaijan and Iran lie within 25 km of the outline of the Caspian Sea. That is what its geometry says, and it is not a statement about who owns the water or where any border runs in it.

Similar in size to Montana

Similar in size to Caspian Sea

More comparisons

Sources and method

Outlines: Lakes and seas: Natural Earth 1:10m physical vectors (public domain), kept only where the measured area is within 10% of the published one. Countries and regions: Natural Earth, 1:10m Admin 0 and Admin 1, public domain.
Boundary: De facto, as drawn by Natural Earth. A lake or a sea has no legal boundary of its own; the outline is a cartographic one.
Area: Measured on the WGS84 ellipsoid from the full-detail outlines, shown rounded. The published figure comes from Wikidata (CC0), fetched 2026-11-11, and is shown beside the measured one.
Drawing: Each outline is projected with an equal-area projection centred on its own centroid, so areas stay true and the two can be laid over each other.
Data built: 2026-11-11

Full method