Difference Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb

Edited by Diffzy | Updated on: August 08, 2022


Difference Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb Difference Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb

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The United States and the United Kingdom were two of the allied nations that created two powerful atomic bombs during World War II. Hiroshima and Nagasaki, Japan, and surrounding areas were the intended target cities for the bombs. On the instructions of American President Harry S. Truman, these two destructive nuclear missiles were launched upon the hapless cities in August 1945. However, there are several differences between the two explosives, which this article will outline.

Hiroshima Atomic Bomb vs Nagasaki Atomic Bomb

The primary distinction between the atomic bombs used in Hiroshima and Nagasaki is that Little Boy, the Hiroshima bomb, included a highly concentrated Uranium-235, whilst Fat Man, the Nagasaki weapon, was made of plutonium. Seven months before World War II started, in January 1939, the race for atomic power reached its breaking point.

Hiroshima's city core, which was heavily inhabited by wooden dwelling buildings and business facilities, was destroyed by the bomb. These factors contributed to the very high levels of fatality and destruction in Hiroshima. Five square miles or 13 square kilometers of Hiroshima were devastated by the firestorm. Nearly 63 percent of Hiroshima's buildings were destroyed, while more sustained significant damage.

Out of the 174,000 residents in Nagasaki, 20,000 died on that day, and an additional 17,000 died during the following four months. Fat Man, a plutonium-based atomic weapon with a significantly more sophisticated structure than the earlier bomb, was the warhead that obliterated the city.

Difference Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb in Tabular Form

Table: Hiroshima Atomic Bomb vs Nagasaki Atomic Bomb
Parameters of Comparison
Hiroshima Atomic Bomb
Nagasaki Atomic Bomb
Hiroshima's city center, which was heavily populated with wooden house structures and business institutions, was the target of the bomb's explosion. These factors contributed to the very high levels of fatality and destruction in Hiroshima.
Even though the Nagasaki nuclear attack was disastrous and about 22.7% of Nagasaki's buildings were destroyed by fire, fewer people died and less damage was caused than in Hiroshima.
The Hiroshima atomic bomb had a simpler construction and was composed of uranium 235.
Plutonium, which has a complicated structure, was used to make the Nagasaki atomic bomb.
A total of 74000 Hiroshima city residents—including military personnel—were killed when the nuclear bomb hit.
In Nagasaki, the impact killed almost 20,000 people.
Bomb Name
The "Little Boy" label was placed on the Hiroshima warhead.
The "Fat Man" nickname was used for the Nagasaki Atomic Bomb.
Time and Date
6 of August 1945
9th August 1945.

What is Hiroshima Atomic Bomb?

The city of Hiroshima, which lies on the southern coast of the Japanese island of Honshu, had about 350,000 residents when the atomic bomb was detonated (including military people). Out of a population of 350,000, the total number of fatalities in Hiroshima has been calculated to be between 100,500 and 180,000. A huge number of people died all at once, and many more perished in the days and months that followed.

The atomic bomb that was dropped on Hiroshima on August 6, 1945, was known as the "Little Boy." Uranium-235 which had been highly enriched and measured was used to build it. This warhead was produced using a particular Diffusion Enrichment Approach. The two primary isotopes U-235, which makes up 0.7 percent of uranium, and U-238, which naturally exists in large quantities, were examined for minute differences in weight.

Similar to UF 6, the difference in weight between the two molecules is only 1%. The unusually high abundance of the rare isotope was influenced by this characteristic. The bomb, which destroyed 90 percent of Hiroshima, had more than 60 kilograms of highly enriched uranium.

These two tragedies are still felt today and are the strongest indicators of the destruction that chemical weapons may cause.

Along with the staggering death toll, those who survived the first blast and firestorms also suffered from radiation sickness, which included symptoms including severe burns, hair loss, vomiting, and bleeding. This was made worse by the fact that 90% of the medical staff in both cities was killed or injured, and the medical supplies that were available quickly ran out.

The Little Boy was the name of the nuclear weapon that was detonated on Hiroshima on August 6, 1945. Its primary component was highly enriched Uranium-235. The creation of this specific bomb included the Diffusion Enrichment Technique. The focus was on tiny variations in the masses of the two main isotopes of uranium, U-235 (which made up 0.7 percent of the initial uranium) and U-238, which makes up the rest. Similar to UF 6, the difference in mass between the two molecules is as tiny as 1%. The enormous concentration of the less frequent isotope was made possible by this characteristic. The bomb that destroyed 90% of Hiroshima's entire city was made with more than 60 kg of highly enriched uranium.

Germany had submitted by July 1945, ending the European conflict. Japan, however, resisted accepting the conditions outlined in the Potsdam Declaration by the Allies. American authorities believed that invading and conquering the Japanese home islands was the only way to force Japan's total capitulation. Even though an estimated 300,000 Japanese citizens had already perished from famine and air strikes, Japan's rulers remained resolute. In opposition to this, American intelligence intercepts showed that by August 2, Japan had already stationed more than 560,000 soldiers as well as thousands of suicide boats and planes on the island of Kyushu to prepare for the anticipated American invasion of Japan. Additional sources accurately inferred that, in the event of an Allied landing, the Japanese military intended to put all American detainees in Japan to death. These unsettling numbers signaled a more expensive struggle than any that the US had ever engaged in throughout the conflict. When battling against less than 120,000 Japanese soldiers on the island of Okinawa from April to June 1945, US forces lost 49,000 losses, including 12,000 men killed in action. A third of the island's prewar population—at least 110,000 Japanese troops and more than 100,000 civilians—died in the assault. American strategists who were looking ahead to the invasion of Japan were greatly affected by American deaths on Okinawa. Instead of defeating the American military, Japan's commanders wanted to win by inflicting heavy deaths and weakening American public morale.

When he decided to unleash the first atomic bomb, American President Harry S. Truman was faced with this predicament in the summer of 1945. Truman and his military advisers were resolved to use every weapon at their disposal to put a quick end to the war in light of intelligence reports indicating that Japan intended to continue fighting. As a result, neither Truman nor any of his advisers ever discussed whether or not to use the atomic bombs, just how and where to do it. To decide how to utilize the bombs most effectively, the American administration assembled a committee of scientists and military commanders in the spring of 1945. They all agreed that no assurance showing the Japanese the explosives in a remote region would result in the Japanese commanders giving up. Japan needed to be persuaded to submit as soon as possible since the United States only had two atomic bombs on hand in July 1945 and more weapons wouldn't be prepared for use for several more weeks. As the conflict dragged on, hundreds of Chinese, American, and Japanese soldiers perished every day.

What is Nagasaki Atomic Bomb?

The Urakami Valley and a small area of downtown Nagasaki were spared the bombing's catastrophic damage because of Nagasaki's steep terrain and the bombing's focus being away from the city center. The harbor and the historic part of Nagasaki were spared by the steep hills that surrounded the Urakami River.

Despite the disastrous nature of the nuclear attack, which resulted in about 22.7 percent of Nagasaki's structures being destroyed by fire, fewer people died and less damage was caused than in Hiroshima. According to estimates, between 50,000 and 100,000 people perished at Nagasaki, with some passing away immediately and others suffering painful deaths from burns and radiation.

The second atomic bomb that was dropped on Nagasaki on August 9, 1945, was dubbed "The Fat Man." Over 90% of the 8 kilograms of plutonium-239 used to build this was Pu-239. Additionally, the systematic operation of particular nuclear reactors was required for the development of this weapon.

On the other hand, the Fat Man was the name of the second atomic weapon that was dropped on Nagasaki on August 9, 1945. This one contained more than 90% Pu-239 and weighed 8 kg. Additionally, this bomb's construction required the methodical use of specific types of nuclear reactors. The University of Chicago's first artificial reactor, which used graphite of incredibly high purity to slow the neutrons emitted during fission and encourage additional fission, was put to use. When plutonium-239 was produced in this manner, a significantly less complex chemical reaction was possible without the use of an intricate isotope separation procedure. Out of a total population of 174,000, 22,000 people perished in Nagasaki that day, and another 17,000 died over the next four months.

The Little Boy, which was constructed of enriched uranium, had a considerably more straightforward design. The Fat Man, which was constructed of Plutonium, had a far more intricate design.

  • The Hiroshima atomic weapon Little Boy and the Nagasaki atomic bomb Fat Man were both built of highly enriched uranium-235.
  • The chemical design of the former bomb was significantly simpler than that of the latter.

Nagasaki was not among the top two options of the Target Committee, which President Harry Truman formed to choose which Japanese towns would be targeted by the Little Boy and Fat Man atomic bombs. Kokura was designated as the second target after Hiroshima instead. On the island of Kyushu, in the 130,000-person city of Kokura, the Japanese had one of their largest ordnance factories, producing chemical weapons among other things. Strangely, despite being aware of all of this, the Americans have not yet attacked the city in their standard bombing campaign. That was one of the factors that led the Target Committee to believe it would be a wise choice following Hiroshima.

The third option, the port city of Nagasaki, was around 100 miles away from Kokura. It had a more military infrastructure, including two Mitsubishi military plants, and a bigger population of about 263,000. Additionally, Nagasaki was a significant port city. It had not yet sustained substantial damage from American conventional bombardment, similar to Kokura and Hiroshima.

Workers on Tinian island worked arduously to finish the Fat Man bomb and have it ready for use after the bombing of Hiroshima on August 6th. Compared to the Little Boy bomb used at Hiroshima, which utilized uranium-235 in a relatively simple explosive mechanism, this plutonium implosion weapon was far more complex. Fat Man was the outcome of years of agonizing over how to employ plutonium in an atomic bomb by the scientists and ordnance specialists at Los Alamos.

Main Differences Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb in Points

  1. While the Nagasaki atomic bomb was made of plutonium, the Hiroshima atomic bomb was built of highly enriched uranium (Uranium-235).
  2. The chemical design of the first bomb was substantially simpler than that of the second, which was much more complex.
  3. The Nagasaki weapon was known as "Fat Man," whereas the Hiroshima bomb was known as "Little Boy."
  4. Around 74,000 people were killed by the Hiroshima bomb in Hiroshima, and 20,000 by the Nagasaki bomb in Nagasaki.
  5. Despite the Hiroshima bomb's supposedly lower power than the Nagasaki bomb's, Hiroshima's death toll was greater due to the city's higher population density.


The city of Hiroshima, which lies on the southern coast of the Japanese island of Honshu, had about 350,000 residents when the atomic bomb was detonated (including the military). Little Boy was the name of the bomb that obliterated the city. At the time, Nagasaki, which is located on the western side of the Japanese island of Kyushu, had a population of around 250,000 people. However, because of the Urakami River, fewer people died there than in Hiroshima. With the plutonium bomb "Fat Man," it was attacked.



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"Difference Between Hiroshima Atomic Bomb and Nagasaki Atomic Bomb." Diffzy.com, 2023. Mon. 20 Mar. 2023. <https://www.diffzy.com/article/difference-between-hiroshima-atomic-bomb-and-nagasaki-829>.

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