List of Build Up: Vocal Boy Group Survival contestants

Build Up: Vocal Boy Group Survival is a South Korean reality competition show, where male vocalists ranging from current and former idol members, soloists, singer-songwriters, musical actors and individual trainees are competing to debut in a four-member vocal boy group. The 40 contestants are divided into four type of voice colors: Allround, Soul, Power, and Unique. After the final episode, the final top four contestants were selected to debut as members of the boy band, B.D.U (Boys Define Universe).

Contestants
The English names of contestants are presented in accordance with the official website.

{{Legend|#EB5406|border=solid 1px #AAAAAA|Final members of B.D.U}} {{Legend|#90C0FF|border=solid 1px #AAAAAA|Contestant eliminated in the finals}} {{Legend|#57BCBE|border=solid 1px #AAAAAA|Contestant eliminated in the semifinals}} {{Legend|#90EE90|border=solid 1px #AAAAAA|Contestant eliminated in the fourth round}} {{Legend|#FFC06F|border=solid 1px #AAAAAA|Contestant eliminated in the third round}} {{Legend|salmon|border=solid 1px #AAAAAA|Contestant eliminated in the second round}} {{Legend|#F7DC6F|border=solid 1px #AAAAAA|Top 4 for the Episode}}
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Voice Check-in (Episode 1)
The Voice Check-in involved all the participating contestants to listen to each other's voice files and vote for the voice they want to build up with. The self-assessment is based on the votes of other 39 contestants.


 * Key
 * Name – Allround
 * Name – Soul
 * Name – Power
 * Name – Unique

Pre-4 Mission (Episode 1–2)
For the Pre-4 Mission, each contestant chose a song and formed a 4-member group to perform a single stage. The ranking on Voice Check-in has a big impact for this mission and if the song has filled with four members, the lower placed contestant must choose another song. Although it is a group mission, the evaluation is individual, and the most voted team member by the judges becomes the top tier and has the right to select the lower tier from the team.

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2 vs 2 Rival Mission (Episode 3–5)
In 2 vs 2 Rival Mission, contestants formed a duet and competed against another duet. The top tiers from Pre-4 Mission can partner with anyone in all sections (Top, Middle and Low), the same matching rule applies with middle tiers but only to sections M and L while low tiers can only team up in their respective section. Another rule is the low tier contestant cannot refuse the top tier contestant's offer to form a team and if picked by more than two then the contestant could choose his partner. The duet with a higher judge score wins and the losing team is a candidate for elimination.

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Triple Death Match Mission (Episode 5–7)
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One Team Mission (Episode 8)
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Semifinal Mission (Episode 9)
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Final Mission (Episode 10)
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