Baltic Sea and Montana are almost exactly the same size

The Baltic Sea (sea) covers about 381,000 km² (147,000 mi²) and Montana (state) about 379,000 km² (147,000 mi²). Their outlines are laid over each other below at one scale. The Baltic Sea outline is Natural Earth’s, checked against the published area.

381,000km²Baltic Sea
379,000km²Montana

200 km

Baltic Sea
Montana

Baltic Sea: Natural Earth draws the Baltic Sea as its main basin and cuts out the Gulf of Bothnia, the Gulf of Finland, the Gulf of Riga and the Bay of Mecklenburg. This page adds them back; the Kattegat and the Danish straits are not counted.

What fits

Montana is 100% of the size of Baltic Sea.
The measured areas differ by 1,830 km², less than half a percent: closer than the measurement itself is certain.
Measured in Belgiums: Baltic Sea is about 12.4, Montana about 12.4.

How they differ

Their centres are about 7,360 km apart.
A standard web map misstates the comparison: Baltic Sea at 59°N is drawn about 3.7× too large and Montana at 47°N about 2.2×, so the map shows Baltic Sea as 1.74× the size of Montana instead of 1.00×.
Together Baltic Sea and Montana cover 761,000 km², close to the size of Zambia (752,000 km², 1.2% smaller).
Baltic Sea's centre is 11.8° of latitude, about 1,310 km, farther north than Montana's.
The Baltic Sea is a sea and ranks 15th of the 40 seas on sizeversus by area if counted as one.
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.
Laid out flat, the Baltic Sea stretches about 1,320 km north to south and 1,160 km east to west; Montana about 527 km by 916 km.
Counted as one, the 5 pieces measure 381,000 km². The published figure for the whole, 377,000 km² (Wikidata, for the whole), is 1.1% below it.

Who wins on what

Measure	Winner	By
Larger area	Baltic Sea	1.00×
Farther north	Baltic Sea	11.8° of latitude
Stretched more on a web map	Baltic Sea	3.7× against 2.2×

Both against the same yardsticks

Yardstick	Baltic Sea	Montana
Belgium 30,700 km²	12.4×	12.4×
United Kingdom 244,000 km²	1.56×	1.56×
Germany 358,000 km²	1.07×	1.06×
Japan 374,000 km²	1.02×	1.02×
France 548,000 km²	0.70×	0.69×
India 3,151,000 km²	0.12×	0.12×
Brazil 8,473,000 km²	0.05×	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

	Baltic Sea	Montana
Is a	Sea5 pieces counted together	StateUnited States
Area, measured	381,000 km²147,000 mi²	379,000 km²147,000 mi²
Area, published	377,000 km²Wikidata	381,000 km²Wikidata
Rank by area	15th of 40seas	–
Greatest depth	459 mWikidata	–
Latitude range	54°N to 66°N	44°N to 49°N
On the shore	8 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 Sweden, Finland, Estonia, Russia, Germany, Latvia, Poland and Denmark lie within 25 km of the outline of the Baltic 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 Baltic Sea

Similar in size to Montana

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