The exact date of birth of Uthman is not known with any degree of certainty. There is also some controversy about the exact age attained by Uthman. When he died in 656 C.E. some said that he was eighty-five, while others said that he was eighty. There were some persons who held that he was only sixty-three.
The Holy Prophet died at the age of sixty-three. Abu Bakr died at the same age. The age of Umar at the time of his martyrdom was also around sixty-three. The age of sixty-three thus acquired a particular sanctity among the Muslims, and this age was attributed by some persons to Uthman merely as a mark of sanctity.
The weight of available evidence is to the effect that Uthman was eighty years old at the time of his martyrdom. On this basis it can be computed that Uthman was born around 576 C.E. That was six years after the "Year of the Elephant" the year when Abraha the Christian Viceroy of Yemen invaded Makkah, and had to withdraw having failed in his object. Uthman was younger than the Holy Prophet of Islam by five or six years.
Although the family of Uthman belonged to Makkah they had some property in Taif as well, and Uthman was born in Taif and not in Makkah. As Taif is a hill station, the presumption is that Uthman was born during the summer months of the year 576 C.E.