Dating the beginning of her reign is more difficult, however. Her father's reign began in either 1526 or 1506 BC according to the high and low estimates of her reign, respectively. The length of the reigns of Thutmose I and Thutmose II, however, cannot be determined with absolute certainty. With short reigns, Hatshepsut would have ascended the throne 14 years after the coronation of Thutmose I, her father. Longer reigns would put her ascension 25 years after Thutmose I's coronation. Thus, Hatshepsut could have assumed power as early as 1512 BC, or, as late as 1479 BC.