At 81 years and 243 days old, Queen Elizabeth II becomes the Britain's oldest-ever monarch Thursday, passing Queen Victoria.
Buckingham Palace has calculated her age down to the hour and says Elizabeth will officially set the new record at around 5 p.m. Greenwich Mean Time, or noon EST, the Associated Press reports.
Elizabeth was born on April 21, 1926. She ascended to the throne in February 1952, when she was 25 years old.
She still has some way to go if she is to set another record held by Victoria – that of longest-reigning monarch. Victoria became queen at 18 and reigned for 63 years and seven months. Elizabeth would pass that mark on Sept. 9, 2015, when she would be 89 years old.
Elizabeth became a grandmother for the eighth time on Monday, when Prince Edward and his wife Sophie welcomed a baby boy