Thank you for the biblical question on Keturah, “How old was Keturah when she got married to Abraham?”
The age of Keturah is uncertain, but it is likely that she was a mature woman. Abraham marries her after his wife, Sarah dies in Genesis 23. It is after Issac marries Rebekah that Abraham marries Keturah.
Genesis 25 says this in the NIV, “Abraham had taken another wife, whose name was Keturah. 2 She bore him Zimran, Jokshan, Medan, Midian, Ishbak and Shuah. 3 Jokshan was the father of Sheba and Dedan; the descendants of Dedan were the Ashurites, the Letushites and the Leummites. 4 The sons of Midian were Ephah, Epher, Hanok, Abida and Eldaah. All these were descendants of Keturah.
5 Abraham left everything he owned to Isaac. 6 But while he was still living, he gave gifts to the sons of his concubines and sent them away from his son Isaac to the land of the east. 7 Abraham lived a hundred and seventy-five years. 8 Then Abraham breathed his last and died at a good old age, an old man and full of years; and he was gathered to his people. 9 His sons Isaac and Ishmael buried him in the cave of Machpelah near Mamre, in the field of Ephron son of Zohar the Hittite, 10 the field Abraham had bought from the Hittites.[a] There Abraham was buried with his wife Sarah. 11 After Abraham’s death, God blessed his son Isaac, who then lived near Beer Lahai Roi.”
it is interesting to note that Abraham had other concubines and sons. Nearing his death, he sends off the sons of his concubines, but not the concubines themselves as far as I know so that Isaac is the sole heir of Abraham.
Keturah had six children from Abraham. This would imply that she was more than just a companion at his old age and being able to have children.
Summary: The age of Keturah is unknown, but it is likely that she was at least a young lady.
-Kingston