There are 17 weight classes in professional boxing, and five major recognised belts for each of the divisions: The WBA (World Boxing Association), WBC (World Boxing Council), IBF (International Boxing Federation), WBO (World Boxing Organization) and The Ring.
There are four recognised major bodies in boxing, the WBA, WBC, IBF and the WBO. The Ring title is awarded by American boxing magazine, The Ring, and has been done since 1922.
The mixture of belts and champions means that there is only a rare occasion when a class can be fully unified to produce an undisputed champion.
Boxers often fight across weight classes in order to maximise their chances of success, and Manny Pacquiao is currently the only fighter to have won titles in eight divisions.
Here is every champion in each of boxing's weight class.
Heavyweight
- WBA: Oleksandr Usyk
- WBC: Oleksandr Usyk
- IBF: Daniel Dubois
- WBO: Oleksandr Usyk
- The Ring: Oleksandr Usyk
Bridgerweight
- WBA: Muslim Gadzhimagomedov
- WBC: Lawrence Okolie
Cruiserweight
- WBA: Gilberto Ramirez
- WBC: Noel Gevor Mikaelian
- IBF: Jai Opetaia
- WBO: Chris Billam-Smith
- The Ring: Jai Opetaia
Light heavyweight
- WBA: Dmitry Bivol
- WBC: Artur Beterbiev
- IBF: Artur Beterbiev
- WBO: Artur Beterbiev
- The Ring: Vacant
Super middleweight
- WBA: Canelo Alvarez
- WBC: Canelo Alvarez
- IBF: Vacant
- WBO: Canelo Alvarez
- The Ring: Canelo Alvarez
Middleweight
- WBA: Erislandry Lara
- WBC: Carlos Adames
- IBF: Janibek Alimkhanuly
- WBO: Janibek Alimkhanuly
- The Ring: Vacant
Super welterweight/Junior middleweight
- WBA: Terence Crawford
- WBC: Sebastian Fundora
- IBF: Bakhram Murtazaliev
- WBO: Sebastian Fundora
- The Ring: Jermell Charlo
Welterweight
- WBA: Terence Crawford
- WBC: Mario Barrios
- IBF: Jaron Ennis
- WBO: Brian Norman Jr.
- The Ring: Vacant
Super lightweight/Junior welterweight
- WBA: Jose Valenzuela
- WBC: Alberto Puello
- IBF: Liam Paro
- WBO: Teofimo Lopez
- The Ring: Teofimo Lopez
Lightweight
- WBA: Gervonta Davis
- WBC: Shakur Stevenson
- IBF: Vasiliy Lomachenko
- WBO: Denys Berinchyk
- The Ring: Vacant
Super featherweight/Junior lightweight
- WBA: Lamont Roach Jr.
- WBC: Robson Conceicao
- IBF: Anthony Cacace
- WBO: Emanuel Navarrete
- The Ring: Vacant
Featherweight
- WBA: Nick Ball
- WBC: Rey Vargas
- IBF: Angelo Leo
- WBO: Rafael Espinoza
- The Ring: Vacant
Super bantamweight/Junior featherweight
- WBA: Naoya Inoue
- WBC: Naoya Inoue
- IBF: Naoya Inoue
- WBO: Naoya Inoue
- The Ring: Naoya Inoue
Bantamweight
- WBA: Takuma Inoue
- WBC: Junto Nakatani
- IBF: Ryosuke Nishida
- WBO: Yoshiki Takei
- The Ring: Vacant
Super flyweight/Junior bantamweight
- WBA: Fernando Martinez
- WBC: Jesse Rodriguez
- IBF: Fernando Martinez
- WBO: Kosei Tanaka
- The Ring: Jesse Rodriguez
Flyweight
- WBA: Seigo Yuri Akui
- WBC: Vacant
- IBF: Angel Ayala
- WBO: Anthony Olascuaga
- The Ring: Vacant
Light/Junior flyweight
- WBA: Vacant
- WBC: Vacant
- IBF: Sivenathi Nontshinga
- WBO: Vacant
- The Ring: Kenshiro Teraji
Minimumweight/Mini flyweight
- WBA: Thammanoon Niyomtrong
- WBC: Melvin Jerusalem
- IBF: Pedro Taduran
- WBO: Oscar Collazo
- The Ring: Vacant
You can read more on how the world championship system works in boxing here.