We’re introduced to Abraham at the end of Genesis 11, where we learn that his father is Terah, his brother is Nahor, and his wife is Sarah. Then from 11:27 to 25:11, we get episodes from his life. Not every episode can be connected to a specific year, but some can. Here are ten events where his age can be known explicitly or implicitly:
- At age 75, Abraham arrived in the land of Canaan (Gen. 12)
- At age 85, Abraham took Hagar as a wife (Gen. 16; 16:3)
- At age 86, Ishmael was born to him by Hagar (Gen. 16:16)
- At age 99, Abraham was circumcised (Gen. 17:24)
- At age 99, Abraham was visited by three travelers (18:1; 18:10)
- At age 100, Isaac was born to him by Sarah (Gen. 21)
- At age 103 (giving approximately three years for Isaac’s weaning), Abraham sent away Ishmael and Hagar (Gen. 21)
- At age 137, Abraham buried his wife who died at 127 (Gen. 23:1)
- At age 140, Abraham’s son Isaac and Rebekah were married (Gen. 24; 25:20)
- At age 175, Abraham died (Gen. 25:7)
From Genesis 12 through 25, the narratives span Abraham’s life from age 75 to 175. In other words, Genesis 12-25 covers one hundred years.
Unto Him 
Where does Keturah and her six sons by Abraham fit in?
Great question. It’s not clear when Abraham married Keturah, so I didn’t include that event in my list. I only included events where his age was explicit or could be implied from other evidence.
You have forgotten the pivotal event of Abraham’s life, for which he is called righteous because of his faith: The sacrifice of Isaac where God provides a ram instead.
Hi Marjorie,
I didn’t forget the event. I didn’t include it in the list because the Bible isn’t clear on Abraham’s age when he went to sacrifice Isaac. My list only includes events where Abraham’s age could be known explicitly or implicitly through other evidence. So as important as the episode in Genesis 22 is, we don’t how old Abraham was when it happened.