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: Oleksandr Usyk

IBF: Oleksandr Usyk

WBA: Oleksandr Usyk*

WBC: Tyson Fury

*Joe Joyce is the WBO interim heavyweight champion

**Daniel Dubois is the WBA "regular" heavyweight champion

Cruiserweight (200 lbs.)

WBO: Lawrence Okolie

IBF: Jai Opetaia

WBA: Arsen Goulamirian

WBC: Badou Jack

Light heavyweight (175 lbs.)

WBO: Artur Beterbiev

IBF: Artur Beterbiev

WBA: Dmitry Bivol

WBC: Artur Beterbiev

Super middleweight (168 lbs.)

WBO: Canelo Alvarez*

IBF: Canelo Alvarez

WBA: Canelo Alvarez**

WBC: Canelo Alvarez***

*John Ryder is the WBO interim super middleweight champion

**David Morrell is the WBA "regular" super middleweight champion

***David Benavidez is the WBC interim super middleweight champion

Middleweight (160 lbs.)

WBO: Janibek Alimkhanuly

IBF: Vacant

WBA: Vacant*

WBC: Jermall Charlo**

*Erislandy Lara is the WBA "regular" middleweight champion

**Carlos Adames is the WBC interim champion

Junior middleweight (154 lbs.)

WBO: Jermell Charlo*

IBF: Jermell Charlo

WBA: Jermell Charlo

WBC: Jermell Charlo**

*Tim Tszyu is the WBO interim junior middleweight champion

**Brian Mendoza is the WBC interim junior middleweight champion

Welterweight (147 lbs.)

WBO: Terence Crawford

IBF: Errol Spence Jr.*

WBA: Errol Spence Jr.**

WBC: Errol Spence Jr.

*Jaron Ennis is the IBF interim welterweight champion

**Eimantas Stanionis is the WBA "regular" champion

Junior welterweight (140 lbs.)

WBO: Josh Taylor

IBF: Subriel Matias

WBA: Alberto Puello

WBC: Regis Prograis

Lightweight (135 lbs.)

WBO: Devin Haney

IBF: Devin Haney

WBA: Devin Haney*

WBC: Devin Haney**

*Gervonta Davis is the WBA "regular" lightweight champion

**Devin Haney is the WBC "franchise" lightweight champion

Junior lightweight (130 lbs.)

WBO: Emanuel Navarrete

IBF: Joe Cordina

WBA: Hector Luis Garcia

WBC: O'Shaquie Foster

Featherweight (126 lbs.)

WBO: Robeisy Ramirez

IBF: Luis Alberto Lopez

WBA: Mauricio Lara

WBC: Rey Vargas

Junior featherweight (122 lbs.)

WBO: Stephen Fulton

IBF: Marlon Tapales

WBA: Marlon Tapales

WBC: Stephen Fulton

Bantamweight (118 lbs.)

WBO: Vacant

IBF: Vacant

WBA: Takuma Inoue

WBC: Vacant

Junior bantamweight (115 lbs.)

WBO: Kazuto Ioka

IBF: Fernando Martinez

WBA: Joshua Franco

WBC: Juan Francisco Estrada*

*Juan Francisco Estrada is the WBC "franchise" junior bantamweight champion

Flyweight (112 lbs.)

WBO: Jesse Rodriguez

IBF: Sunny Edwards

WBA: Artem Dalakian

WBC: Julio Cesar Martinez*

*McWilliams Arroyo is the WBC interim flyweight champion

Junior flyweight (108 lbs.)

WBO: Jonathan Gonzalez

IBF: Sivenathi Nontshinga

WBA: Kenshiro Teraji

WBC: Kenshiro Teraji

Strawweight (105 lbs.)

WBO: Melvin Jerusalem

IBF: Daniel Valladares

WBA: Knockout CP Freshmart*

WBC: Petchmanee CP Freshmart

*Erick Rosa is the WBA "regular" strawweight champion