It depends on the measurement. The traditional answer is yes — the Nile (6,650 km / 4,132 mi) is longer than the Amazon (6,400 km / 3,976 mi), making the Nile the world's longest river. But 2007 and 2014 expeditions argued the Amazon's true length is closer to 6,992 km (4,345 mi), which would make the Amazon the longest. The debate remains unresolved, and most major sources still call the Nile the world's longest river.
The Short Answer
For over a century, geography textbooks have called the Nile the world's longest river. Its 6,650-km length from Lake Victoria in East Africa to the Mediterranean Sea has been the standard answer. But measuring river length is more difficult than it sounds, and the Amazon vs Nile question has been disputed by researchers for decades.
The dispute hinges on where exactly each river starts and ends, how to measure meandering channels, and which tributary you consider the "true" source. Both rivers have multiple plausible source points and complex deltas where the river meets the sea. Different measurement methods produce different results — and the Amazon's case for being the world's longest has strengthened in recent years.
The Real Numbers (As Conventionally Measured)
- Nile River: 6,650 km (4,132 mi) — Lake Victoria to Mediterranean
- Amazon River: 6,400 km (3,976 mi) — traditional measurement
- Amazon River: 6,992 km (4,345 mi) — 2007/2014 expedition measurements
- Yangtze: 6,300 km (3,915 mi)
- Mississippi-Missouri: 6,275 km (3,902 mi)
Note: the source of the Nile is traditionally Lake Victoria, but the Nile's upper tributaries extend further upstream. The most distant source is often considered the Kagera River, which flows into Lake Victoria from headwaters in Burundi or Rwanda. Including the Kagera, some measurements push the Nile's length to about 6,720 km or even 6,853 km.
The Source Problem
Every major river has the same issue: where does it start? Rivers are formed by countless small streams joining together. The convention is to follow the longest tributary all the way to its furthest source, but identifying that source is sometimes contested.
The Nile's Source
The Nile flows north from East Africa to the Mediterranean Sea. Its main tributaries are:
- White Nile: Flows from Lake Victoria through Uganda, South Sudan, and Sudan. Its source is the Kagera River in Burundi/Rwanda.
- Blue Nile: Flows from Lake Tana in Ethiopia. Provides about 85% of the Nile's water at Khartoum.
The White Nile is longer; the Blue Nile carries more water. The two meet at Khartoum in Sudan. From Khartoum, the combined Nile flows north through Egypt to the Mediterranean. The "Nile" we measure is typically the White Nile + main channel — total length 6,650 km or so.
The Amazon's Source
The Amazon flows east across South America. Its source has been disputed for centuries. Traditional candidates:
- Apurímac River: A tributary that flows from glaciers in the Peruvian Andes.
- Mantaro River: Another Peruvian tributary, argued by some expeditions to be longer than the Apurímac.
- Marañón River: Joins with the Ucayali to form the official Amazon.
A 2007 Brazilian-Peruvian expedition argued that the Mantaro is the longest tributary, putting the Amazon's headwaters in the southern Peruvian highlands at higher elevation than previously thought. This would extend the Amazon's length to 6,992 km — making it longer than the Nile by about 340 km.
The Mouth Problem
Where does a river end? For the Nile, the answer is fairly clear: the Nile splits into the Damietta and Rosetta distributaries north of Cairo and empties into the Mediterranean. For the Amazon, it's more complicated. The Amazon has the world's largest river mouth — about 240 km across — and pours into the Atlantic Ocean through a maze of channels and the Marajó Island delta.
Some measurements treat the Amazon as ending where it reaches the Atlantic. Others extend it through tidal effects and the freshwater plume that extends up to 200 km into the ocean. Different definitions of the "end" can shift the Amazon's length by tens of kilometers.
How the 2007 Expedition Worked
In June-July 2007, a joint Brazilian-Peruvian National Geographic Society expedition led by Brazilian geographer Régis Filho mapped the Amazon's source using GPS, satellite imagery, and on-the-ground surveying. They argued that previous measurements had missed the true headwaters of the Mantaro River, which they claimed flowed from glaciers about 100 km farther south than the Apurímac sources.
Their reported length: 6,992 km, longer than the Nile by 342 km. This would make the Amazon the world's longest river. The result was published with significant fanfare and accepted by some major geography organizations. However, the result was disputed by other experts who argued that the Mantaro's flow becomes seasonal in dry months, which by convention disqualifies it as the "true" source.
Why It's Hard to Settle
The Nile-vs-Amazon debate is hard to resolve definitively because:
- Source criteria differ: Some experts require year-round flow; others count any headwater stream regardless of seasonality.
- Measurement technology has improved: Older measurements were estimates from maps; modern GPS surveys can give different answers.
- Rivers change: River channels shift over decades, dam construction alters lengths, and meandering changes course.
- National pride: Both rivers have strong cultural and economic significance, and the "world's longest" title affects tourism and identity.
What About Water Volume?
The Amazon wins by water volume — by a huge margin. The Amazon's discharge at its mouth is about 209,000 m³/s, while the Nile's discharge is about 2,830 m³/s. The Amazon carries roughly 74× more water than the Nile. By drainage basin area, the Amazon is also far larger (7.05 million km² vs Nile's 3.4 million km²).
Some argue the Amazon's water volume makes it the "most important" river in the world regardless of the length debate. The Amazon discharges more freshwater into the ocean than the next seven largest rivers in the world combined — about 20% of all freshwater that reaches the world's oceans.
Cultural and Historical Significance
The Nile was the lifeblood of ancient Egyptian civilization — pharaonic Egypt depended entirely on the Nile's annual floods for agriculture. The river enabled one of the longest-running continuous civilizations in human history (3000 BC to the present). Cairo, on the Nile, is one of the oldest continuously inhabited capital cities.
The Amazon has its own deep significance. Indigenous peoples have inhabited the Amazon basin for at least 12,000 years. The river system enabled the rise of complex pre-Columbian cultures, including settlements that may have housed up to 10 million people before European contact. The Amazon today is a critical ecosystem for global climate stability — its forests absorb roughly 1.5 billion tons of CO₂ annually.
Modern Consensus
As of 2026, most major geographic organizations still call the Nile the world's longest river, with the Amazon in second place. Key sources:
- Encyclopedia Britannica: Nile (6,650 km)
- Wikipedia: Nile (6,650 km), but notes the dispute
- USGS / National Geographic: Nile traditionally, though some publications now list Amazon
- Brazilian/Peruvian official sources: Amazon (6,992 km)
So the answer depends on which authority you trust. Most American and European sources still favor the Nile. South American sources increasingly favor the Amazon. The debate will likely continue until a definitive, internationally-agreed methodology is established.
Key Facts
- Traditional answer: Nile (6,650 km) is longer than Amazon (6,400 km).
- 2007 expedition: Amazon may be 6,992 km, longer than Nile.
- Amazon discharges 74× more water than the Nile.
- Amazon's drainage basin (7.05M km²) is over 2× the Nile's.
- The world's longest river depends on which source/methodology you accept.
Fun Facts
- The Nile flows through 11 countries (Egypt, Sudan, South Sudan, Ethiopia, Uganda, Tanzania, Kenya, Rwanda, Burundi, DRC, Eritrea).
- The Amazon flows through 7 countries (Brazil, Peru, Bolivia, Colombia, Ecuador, Venezuela, Guyana).
- The Amazon has over 1,100 tributaries, of which 17 are over 1,500 km long.
- The Nile is the only river in the world that flows north toward the equator (most major rivers flow away from their continents' interiors).
- The Amazon's discharge at Manaus is so massive that it pushes the ocean salt boundary 100+ km off the South American coast.
The Bottom Line
By the traditional measurement, the Nile is longer than the Amazon by about 250 km. By the 2007 expedition's measurement, the Amazon is longer by about 342 km. The answer depends on which source's methodology you accept. Most major geography references still call the Nile the world's longest river, but the Amazon's case has been gaining strength for two decades.
What's clear: both rivers are colossal, ancient, civilizationally important, and difficult to measure precisely. The Amazon dwarfs the Nile by water volume. The Nile may dwarf the Amazon by length — or may not, depending on who you ask. Geography is rarely as settled as textbooks suggest.