Callaspo also added a sacrifice fly, as the Royals won for the seventh time in eight games. Robinson Tejeda (3-1) made his third start of the season and allowed just one run on two hits and four walks in five innings.
Carlos Guillen had an RBI single.
The Tigers had only four hits in their sixth loss in eight games. The defeat narrows their division lead over Minnesota to five games.
Jarrod Washburn (9-9) lasted only one inning, giving up four runs, three hits and two walks.
Since joining Detroit in late July, Washburn is 1-3 with a 7.33 earned-run average, and the team is 4-4 in his eight starts.