The Power Level (戦闘力, Sentō Ryoku; literally "combat power" or "fighting strength"), referred to as Battle Power (BP) in video games, is a concept found in the Dragon Ball franchise created by Akira Toriyama. It is first introduced in Dragon Ball, where Goku as a kid learns to sense ki after drinking the Ultra Divine Water, although the Z Fighters are able to detect power levels via the ki sensing ability eventually.
The highest number ever officially read aloud from a scouter is Captain Ginyu's reading of Goku's power level, which after powering up, is 180,000. The highest power level ever mentioned in Dragon Ball Z is Frieza's power level of 530,000, said by Frieza himself while battling Nail. The highest power level ever officially stated in the Daizenshuu guides is Super Saiyan Goku's power level of 150,000,000 while battling Frieza on Namek. The overall highest power level, as stated by V-Jump, is 2,500,000,000 of Super Saiyan Gogeta.
The use of power levels is to get an estimation of how a battle will fare between two opponents of known power levels. In general, if one has a higher power level than one's opponent, then he/she can defeat the one with the weaker power level. For example, "Person A" has a fighting power of 10,000 and "Person B" has a fighting power of 5,000. "Person A" can most certainly defeat "Person B". However, the factors of speed, strength, and technique can also come into factor when deciding the outcome of a fight.
It should be noted that, when factoring in the edge a fighter has over an opponent, the difference in power levels as a flat number is apparently not important, but rather, the relative or percentage difference between the power levels of the two combatants.
Changes in power levels
In general, the power level of a regular person in the Dragon Ball universe seems to remain pretty constant throughout his/her life. Power levels can be increased, usually very slowly, through intense training or by some other special mean. Some people are able to increase their power levels faster than others; the most clear example of this is Goku or Gohan.
The power level of most people is usually the same independent of the fact that they are resting or powered-up. However, there are several important exceptions. The most common way to increase one's power-level temporarily during a fight is for races or characters that are able to transform into different shapes and alter their external appearance. Examples include Saiyans (who transform into Great Apes and Super Saiyans), Zarbon and Frieza. There are also some people that have learned the skill to change their apparent power-level at will, using a Power Up technique. This allows them to "supress" their power-level when they wish to appear weaker, to be undetected or to conserve energy, and to increase their power-levels to their maximum during a fight. Namekians and highly-trained earthlings (such as the Z Fighters) seem to be examples of races that are able to do this with most ease, though Saiyans are also shown to be able to learn this ability. Other characters known to possess this ability are Captain Ginyu and Frieza, whose race is unknown. Some beings like Majin Buu and Cell possess the ability to absorb others to increase their power level.
The movie Dragon Ball Z: The Tree of Might introduces the Fruit of the Tree of Might, a special fruit that gives who ever consumes it a massive power increase, basically giving to those who have access to it a shortcut to obtaining a greater power level with little to no effort.
Saiyans possess a unique ability called Zenkai that allows them to easily increase their permanent power level. If they fight a strong opponent and are left almost dead, but are able to recover, they will gain a great amount of power, and increase their maximum level. The first character to display this in the series is Vegeta. However, it should be noted that it is implied (as part of the series' retroactive continuity) that Goku displayed this ability as well during in his youth in the Dragon Ball series (when Vegeta mentions the ability during his second fight with Zarbon, and Krillin explains that the same thing used to happen to Goku whenever he survived a fierce battle of the same caliber). This ability also extends to Half-Saiyans, like Gohan.
Characters that have mixed Saiyan and human blood seem to display special abilities regarding power levels. They are able to reach high levels much faster than other races. Their power level at a given time also fluctuates a lot depending on their emotional state. Intense rage, for example, can make characters like Gohan or Goku Jr. increase their power level significantly for a limited amount of time.
Influence and similarities on other series
Akira Toriyama and his work in the Dragon Ball series has influence in several other manga work. Similar works use an identical kind of "inner power", and that "inner power" made the characters grow stronger.
- Ring ni Kakero (Shonen Jump,77) authored by Masami Kurumada. Many concepts from this series are similar to Dragon Ball, such as tournament fighting, exciting fighting styles, and chi power.
- Masashi Kishimoto states in a message in his manga, Naruto, that he was influenced by Toriyama. In Naruto, the concept similar to "ki" is called chakra level; the trademark technique being the Rasengan, which requires a high level of chakra control.
- In the manga Saint Seiya, authored by Masami Kurumada, the protagonist Seiya is the titular character of the namesake show. He is one of the 88 saints of Athena, and serves loyally at her side. Seiya dons the bronze cloth (an armor that denotes sainthood) of Pegasus, and draws power ("cosmos") from the constellation that connects to it. The saints can grow stronger if they raise higher levels of "cosmos".
- Bleach is a manga and anime series by Tite Kubo. All Bleach characters are "souls". Living humans contain souls within their bodies. Disembodied souls, or spirits, have a form composed of particles of spiritual energy called "Reiatsu" (霊圧, Spiritual Pressure), Certain unique humans naturally have both the power to sense and the strength to fight with spirits. Ordinary humans can gain the ability to interact with spirits by spending time around a large source of spirit energy. Ichigo Kurosaki is the exact example, and considered to be one of the strongest characters.
- YuYu Hakusho is a manga and anime series by Yoshihiro Togashi. Yu Yu Hakusho characters are either human or yokai (demon), and have spiritual powers called reiki (for humans) and yoki (for demons). There is also a system of yoki class or equivalent-to-yoki class that ranges from E-S+, E being the weakest and S class being the strongest level of yokai. Yokai that are soldiers of one of the three of demon kings, Yomi have devices similar to scouters that let them read an enemy's power level.
- Shaman King is a manga and anime series by Hiroyuki Takei. The Shaman King characters are shamans or mediums that uses a spiritual energy called Furyoku to materialize their spirit guardians. This process is known as Over Soul, and the inner power is measured by an arm device whose function is similar to a Scouter.
- One Piece is a manga and anime series by Eiichiro Oda. Dōriki (道力, literally meaning "Power") is a measurement of the power of one's Rokushiki abilities among the CP9 (Cipher Pol Number 9). It is measured in a similar way to Dragon Ball's power level but in the form of hitting a member of CP9 (Fukurou) who will then after being hit follow on to tell one his Douriki. However, this measurement of power was short-lived and was only ever shown to measure the power of the CP9 members and a single marine.
- Ghost Sweeper Mikami is a manga and anime series by Takashi Shiina. A type of spiritual energy labelled as reiki is common among all the characters in the series. It is measured in a fashion similar to the scouters in Dragon Ball, but in more relation to this manga it is gauged with a ring-shaped measuring device which enlarges from its original ring size, surrounds the target and temporarily drains them of their spiritual energy. The end result is a rating defined as "might" which can alternatively be seen as a power level.
- Claymore, created by Norihiro Yagi, possesses the concept of yoki, which all of the eponymous Claymores (an army of female warriors working for the mysterious Organization) possess. Yoki is also possessed by a group of carnivorous demons called "yokai", with the Claymores being human females that are trained and turned into half-yokai hybrids in order to fight them. The Claymores are all ranked from 1 to 47, with 1 being the strongest and 47 being the weakest. Usually, this ranking is based solely upon the amount of yoki the individual possesses (Clare, the protagonist is only one-quarter yokai and is ranked at 47). Further, only use a small portion of their yoki at any given time, but can tap into more of it at the risk of permanently transforming to beasts known as Awakened Beings.