| Time | Date | Name | Meet |
|---|---|---|---|
| 49.31 | Feb. 17, 2024 | Ethan Yuen | Midwest Conference Championships |
| 49.37 | Dec. 2, 2023 | Ethan Yuen | Pioneer Classic |
| 49.74 | Feb. 18, 2023 | Ethan Yuen | Midwest Conference Championships |
| 50.25 | Feb. 19, 2022 | Ethan Yuen | Midwest Conference Championships |
| 50.93 | Jan. 22, 2022 | Ethan Yuen | Grinnell Invitational |
| 51.14 | Feb. 15, 2020 | Mitchell Sevier | Midwest Conference Championships |
| 51.15 | Feb. 17, 2018 | Mitchell Sevier | Midwest Conference Championships |
| 51.30 | Jan. 20, 2018 | Paul Cover | Grinnell Invitational |
| 51.34 | Feb. 16, 2013 | Emanuel Spooner | Midwest Conference Championships |
| 53.40 | Feb. 25, 2012 | Emanuel Spooner | Pioneer Last Chance Meet |
| 53.91 | Feb. 19, 2011 | Emanuel Spooner | Midwest Conference Championships |
| 55.45 | Feb. 4, 2011 | Michael Brus | Grinnell vs. Coe |
| 55.69 | Jan. 15, 2010 | Michael Schoelz | Grinnell Invitational |
| 57.18 | Jan. 15, 2009 | Nate Wittnam | Grinnell Invitational |
