Sea of Japan is 1.02× the size of Tanzania

The Sea of Japan (sea) covers about 959,000 km² (370,000 mi²) and Tanzania (country) about 942,000 km² (364,000 mi²). Below, both outlines are drawn at one scale and centred on each other. The Sea of Japan outline is Natural Earth’s, checked against the published area.

959,000km²Sea of Japan
942,000km²Tanzania

200 km

Sea of Japan
Tanzania

What fits

Tanzania is 98% of the size of Sea of Japan.
Sea of Japan is larger by 17,100 km² (6,600 mi²), which is 1.8% of the area of Tanzania.
Measured in Belgiums: Sea of Japan is about 31.3, Tanzania about 30.7.

How they differ

Their centres are about 11,400 km apart.
A standard web map misstates the comparison: Sea of Japan at 41°N is drawn about 1.8× too large and Tanzania at 6°S about 1.0×, so the map shows Sea of Japan as 1.77× the size of Tanzania instead of 1.02×.
Together Sea of Japan and Tanzania cover 1,900,000 km², close to the size of Indonesia (1,880,000 km², 1.1% smaller).
The gap between them, 17,100 km², is about the size of Eswatini (17,100 km²).
Sea of Japan's centre is 47.4° of latitude, about 5,270 km, farther north than Tanzania's.
The Sea of Japan is a sea and ranks 9th of the 42 seas on sizeversus by area.
Tanzania ranks 31st of 212 countries by area.
Laid out flat, the Sea of Japan stretches about 1,960 km north to south and 1,130 km east to west; Tanzania about 1,190 km by 1,220 km.
Poured over Tanzania, the 1,630,000 km³ that Wikidata records for the Sea of Japan would stand 1,731 m deep.
Wikidata’s published figure of 978,000 km² agrees with our measured 959,000 km², to within 2%.

Who wins on what

Measure	Winner	By
Larger area	Sea of Japan	1.02×
Farther north	Sea of Japan	47.4° of latitude
Stretched more on a web map	Sea of Japan	1.8× against 1.0×

Both against the same yardsticks

Yardstick	Sea of Japan	Tanzania
Belgium 30,700 km²	31.3×	30.7×
United Kingdom 244,000 km²	3.93×	3.86×
Germany 358,000 km²	2.68×	2.63×
Japan 374,000 km²	2.57×	2.52×
France 548,000 km²	1.75×	1.72×
India 3,151,000 km²	0.30×	0.30×
Brazil 8,473,000 km²	0.11×	0.11×
United States 9,447,000 km²	0.10×	0.10×
Russia 16,980,000 km²	0.06×	0.06×

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

Side by side

	Sea of Japan	Tanzania
Is a	Seasea on sizeversus	CountryAfrica
Area, measured	959,000 km²370,000 mi²	942,000 km²364,000 mi²
Area, published	978,000 km²Wikidata	947,000 km²Wikidata
Rank by area	9th of 42seas	31st of 212countries
Greatest depth	3,742 mWikidata	–
Volume	1,630,000 km³	–
Latitude range	34°N to 52°N	12°S to 1°S
On the shore	4 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 Japan, Russia, North Korea and South Korea lie within 25 km of the outline of the Sea of Japan. 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 Sea of Japan

Similar in size to Tanzania

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