Hanoi
3,359 km²
Rio de Janeiro
1,221 km²
Vietnam
Brazil
Area Comparison
Hanoi is 2.8x larger than Rio de Janeiro
Population Comparison
Hanoi has 1.2x more people than Rio de Janeiro
Hanoi is significantly larger, covering 2.8 times the area of Rio de Janeiro. Hanoi spans 3,359 km² (1,297 mi²) while Rio de Janeiro covers 1,221 km² (471 mi²) — a difference of 2,138 km². You could fit Rio de Janeiro inside Hanoi approximately 2 times.
To put Hanoi's size in perspective, its area of 3,359 km² is about 1.2x smaller than Rhode Island. Meanwhile, Rio de Janeiro at 1,221 km² is about 1.3x smaller than London.
Hanoi's footprint is roughly about 470,000 American football fields, 57 times the area of Manhattan, or 32 times the area of Paris — pick whichever unit feels intuitive. Rio de Janeiro works out to about 171,000 American football fields, 21 times the area of Manhattan, or 12 times the area of Paris.
Hanoi is the capital and second-most populous municipality of Vietnam. It encompasses an area of 3,358.6 km2 (1,296.8 mi2), and as of 2025 has a population of 8,807,523. Hanoi had the second-highest gross regional domestic product of all Vietnamese provinces and municipalities at US$48 billion in 2023, behind Ho Chi Minh City. It hosts 78 foreign embassies, the headquarters of the Vietnam People's Army (VPA), its Vietnam National University system, and other governmental organizations.
Known as "City Between Rivers", Hanoi covers 3,359 km² with a population of 8.1 million. The city was established in 1010. Hanoi is known for Hoan Kiem Lake, Old Quarter, Temple of Literature, among other attractions. The city's main transit system is the Hanoi Metro.
Hanoi encompasses 3,358.6 square kilometers and had a population of nearly 8.8 million as of 2025.
Rio de Janeiro, also known simply as Rio, is the capital of the state of Rio de Janeiro. It is the second-most-populous city in Brazil after São Paulo and the sixth-most-populous city in the Americas.
Also known as "Cidade Maravilhosa", Rio de Janeiro has an area of 1,221 km² and is home to 6.8 million people. Its history stretches back to 1565. Visitors come for Christ the Redeemer, Sugarloaf Mountain, Copacabana beach, and much more. Getting around is easy with the MetrôRio.
Rio de Janeiro is the second-most-populous city in Brazil after São Paulo and the sixth-most-populous in the Americas.
Looking beyond city limits, the Rio de Janeiro metropolitan area covers 6,744 km², which is 2.0x larger than greater Hanoi at 3,359 km². The Rio de Janeiro metro area is also more populous, with 13.5 million people compared to 8.1 million.
Hanoi has a population density of 2,397 people per km² — a moderately dense city. Rio de Janeiro, with 5,528 people per km², is a densely populated city. Rio de Janeiro is noticeably denser, packing 2.3 times more people per square kilometer.
This comparison spans continents — Hanoi in Asia versus Rio de Janeiro in South America. Despite the geographic distance, comparing their sizes reveals surprising insights about how cities grow worldwide.
Hanoi has a humid subtropical climate while Rio de Janeiro experiences tropical savanna conditions. When it's noon in Hanoi, it's 2:00 AM in Rio de Janeiro — a 10-hour time difference.
Size Ratio
Rio de Janeiro fits inside Hanoi ~2 times
Density Gap
Rio de Janeiro is 2.3x more densely populated
Time Difference
10 hours apart
History
Hanoi is ~555 years older
Hanoi covers 3,359 km². Cities with a similar urban footprint include Karachi (3,527 km²), Cairo (3,085 km²), Dubai (4,114 km²), Lima (2,672 km²), or Moscow (2,511 km²).
Rio de Janeiro covers 1,221 km². Cities with a similar urban footprint include San Antonio (1,209 km²), Lagos (1,172 km²), Rome (1,285 km²), Los Angeles (1,302 km²), or Hong Kong (1,114 km²).
The straight-line distance from Hanoi to Rio de Janeiro is 16,818 km (10,450 miles), with an estimated flight time of ~20h 17m.
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