Kalkbrenner played basketball for Trinity Catholic High School in St. Louis, Missouri.[1] As a junior, he averaged 13.9 points, 7.6 rebounds and 3.9 blocks per game, earning AAA Player of the Year and Class 3 All-State honors.[2][3] Kalkbrenner competed for Mac Irvin Fire on the Amateur Athletic Union circuit, and was named Nike Elite Youth Basketball League Defensive Player of the Year in 2019.[4] In his senior season, Kalkbrenner averaged 16.3 points, 11 rebounds and 5.7 blocks per game, repeating as a Class 3 All-State selection.[5] A consensus four-star recruit, he committed to playing college basketball for Creighton over offers from Stanford, Purdue and Kansas.[6]
College career
Kalkbrenner came off the bench in his freshman season at Creighton. On December 17, 2020, he recorded a season-high 15 points and five rebounds in a 94–76 win over St. John's.[7] As a freshman, Kalkbrenner averaged 5.9 points, 3.5 rebounds and 1.2 blocks per game, leading all Big East freshmen in blocks.[8] On February 12, 2022, he scored a career-high 22 points and had 15 rebounds in an 80–66 win against Georgetown.[9] Kalkbrenner was named Honorable Mention All-Big East as well as Defensive Player of the Year.[10][11] He suffered a knee injury in a 72–69 overtime win over San Diego State in the NCAA Tournament, ending his season. Kalkbrenner averaged 13.1 points and 7.7 rebounds per game.[12]
During the following NCAA tournament, Kalkbrenner scored a career-high 31 points during a 72–63 first round win over NC State.[13]
On October 23, 2024, he was named 2024-2025 Big East Conference Preseason Player of the Year.[14] On November 6, he scored a career-high 49 points in a win over the UT Rio Grande Valley Vaqueros and set a Bluejays record with 20 made field goals.[15]
National team career
Kalkbrenner represented the United States at the 2021 FIBA Under-19 World Cup in Latvia. He averaged 5.9 points, four rebounds and 1.3 blocks per game, helping his team win the gold medal.[16]