Possibly in his 40's-50's, the Bible does not say, but Jewish extra-biblical sources say he was an older man (not aged) and Jesus had brothers and sisters, so he can't have been too old to father children.
No one really knows for sure. A lot of people just guess or make up random ages. Ask 20 different people and you will get many different answers. A lot of artwork portrays Joseph and Mary as roughly...
The Hebrew word Almah refers to a young girl that reaches puberty but still under the care of her parents. Mary being an Almah may have been espoused to Joseph as early as when she was 12 years old....
Nowhere in the Bible is it suggested that Joseph had already been married before marrying Mary, and there is no extra-biblical evidence of this, or that he was a widower.
A later Christian...
I'm going to assume that this questioner means at the time she was pregnant with Jesus... Scholars speculate that Mary probably only about 12 or 13 years old when she became pregnant with Jesus. This...