Heats
vendredi 10 août 2018, 03h00 GMT – 03h00 GMT
| Nom | Équipe | Temps | |
|---|---|---|---|
| 1 |  Zane Grothe | United States | 3′ 45.32″ |
| 2 |  Jack McLoughlin | Australia | + 0.09″ |
| 3 | Mack Horton | Australia | + 2.43″ |
| 4 | Grant Shoults | United States | + 2.91″ |
| 5 | Conor Dwyer | United States | + 3.28″ |
| 6 | Elijah Winnington | Australia | + 3.95″ |
| 7 | Naito Ehara | Japan | + 4.85″ |
| 8 |  Robert Finke | United States | + 5.91″ |
| 9 |  Fernando Scheffer | Brazil | + 6.46″ |
| 10 | Sean Grieshop | United States | + 6.72″ |
| 11 | Shogo Takeda | Japan | + 6.91″ |
| 12 | Townley Haas | United States | + 8.04″ |
| 13 | Wesley Roberts | Cook Islands | + 8.76″ |
| 14 | Kohei Yamamoto | Japan | + 9.52″ |
| 15 | Tristan Cote | Canada | + 9.62″ |
| 16 | Ayatsugu Hirai | Japan | + 10.06″ |
| 17 | Alex Pratt | Canada | + 10.34″ |
| 18 | Peter Brothers | Canada | + 10.48″ |
| 19 | Luiz Altamir Melo | Brazil | + 10.53″ |
| 20 | Noel Keane | Palau | + 42.89″ |
| 21 | Mark Imazu | Guam | + 1′ 2.69″ |
| Jeremy Bagshaw | Canada | DQ |