With 17 weight classes in boxing and four major sanctioning bodies that bestow world titles, keeping track of who holds each of the belts can be difficult -- especially when there are sometimes multiple titlists in each organization because of interim and secondary belts.

To make it easier for boxing fans, below is a quick reference chart of who holds each of the titles in the four organizations

To check the top 10 fighters in each division, visit ESPN's divisional rankings.

For a list of the best fighters regardless of weight class, check ESPN's pound-for-pound rankings.

Heavyweight (Unlimited)

WBO: Fabio Wardley

IBF: Oleksandr Usyk

WBA: Oleksandr Usyk*

WBC: Oleksandr Usyk**

*Murat Gassiev is the WBA "regular" heavyweight champion

**Agit Kabayel is the WBC interim heavyweight hampion

Cruiserweight (200 lbs.)

WBO: Gilberto Ramirez

IBF: Jai Opetaia

WBA: Gilberto Ramirez

WBC: Norair Mikaeljan

Light heavyweight (175 lbs.)

WBO: Dmitry Bivol*

IBF: Dmitry Bivol

WBA: Dmitry Bivol**

WBC: David Benavidez

*Callum Smith is the WBO interim light heavyweight champion

**David Benavidez is the WBA "regular" light heavyweight champion

Super middleweight (168 lbs.)

WBO: Vacant

IBF: Vacant

WBA: Jose Armando Resendiz

WBC: Vacant*

*Christian Mbilli is the WBC interim super middleweight champion

Middleweight (160 lbs.)

WBO: Janibek Alimkhanuly

IBF: Janibek Alimkhanuly

WBA: Erislandy Lara

WBC: Carlos Adames

Junior middleweight (154 lbs.)

WBO: Xander Zayas

IBF: Bakhram Murtazaliev

WBA: Abass Baraou*

WBC: Sebastian Fundora**

*Jaron Ennis is the WBA interim junior middleweight champion

**Vergil Ortiz Jr. is the WBC interim junior middleweight champion

Welterweight (147 lbs.)

WBO: Devin Haney

IBF: Lewis Crocker

WBA: Rolando Romero

WBC: Mario Barrios

Junior welterweight (140 lbs.)

WBO: Teofimo Lopez Jr.

IBF: Richardson Hitchins

WBA: Gary Antuanne Russell

WBC: Dalton Smith*

*Isaac Cruz is the WBC interim junior welterweight champion

Lightweight (135 lbs.)

WBO: Abdullah Mason

IBF: Raymond Muratalla

WBA: Gervonta Davis

WBC: Shakur Stevenson*

*Jadier Herrera is the WBC interim lightweight champion

Junior lightweight (130 lbs.)

WBO: Emanuel Navarrete

IBF: Eduardo Nunez

WBA: Lamont Roach*

WBC: O'Shaquie Foster

*James Dickens is the WBA interim junior lightweight champion

Featherweight (126 lbs.)

WBO: Rafael Espinoza

IBF: Angelo Leo

WBA: Nick Ball

WBC: Stephen Fulton*

*Rey Vargas is the WBC featherweight champion in recess and Bruce Carrington is the WBC interim featherweight champion

Junior featherweight (122 lbs.)

WBO: Naoya Inoue

IBF: Naoya Inoue

WBA: Naoya Inoue

WBC: Naoya Inoue

Bantamweight (118 lbs.)

WBO: Christian Medina

IBF: Jose Salas Reyes

WBA: Seiya Tsutsumi

WBC: Vacant

Junior bantamweight (115 lbs.)

WBO: Jesse Rodriguez

IBF: Willibaldo Garcia Perez

WBA: Jesse Rodriguez*

WBC: Jesse Rodriguez

*David Jimenez is the WBA interim junior bantamweight interim champion

Flyweight (112 lbs.)

WBO: Anthony Olascuaga

IBF: Masamichi Yabuki

WBA: Ricardo Sandoval

WBC: Ricardo Sandoval*

*Galal Yafai is the WBC interim flyweight champion

Junior flyweight (108 lbs.)

WBO: Rene Santiago

IBF: Thanongsak Simsri

WBA: Rene Santiago

WBC: Carlos Canizales

Strawweight (105 lbs.)

WBO: Oscar Collazo

IBF: Pedro Taduran

WBA: Oscar Collazo

WBC: Melvin Jerusalem