As we know Avraham was changed from Avram. Does anyone know how old Avraham was when he got his name change?
It seems clear from Bereishit 17:1-5 that he was 99 years old.
According to the sefer סדר הדורות הקצר, p.9 - It writes that in the year 2047 (counted from the creation of the world) Avraham was aged 99 when he performed milah on himself and his sons on the 13th Nissan. It was at this time his name was changed.