Crown calculus: The math behind Queen Victoria’s record reign

Our annotated breakdown of how Windsor Castle’s bibliographer measured the exact minute Queen Elizabeth II will take the crown for longest reign
21 May 1895. Photograph of Queen Victoria (1819-1901), seated in an upholstered chair whilst knitting. A ball of wool lies on the floor next to the Queen. Seated opposite the Queen is her daughter Princess Beatrice (1857-1944), who is reading the newspaper to the Queen in the Queen’s Sitting Room of Windsor Castle. The photograph was taken after breakfast on 21 May 1895, by a Danish photographer who had been specially recommended by the Princess of Wales, herself a Danish Princess. Mary Steen/Her Majesty Queen Elizabeth II/Royal Collection Trust CREDIT: Her Majesty Queen Elizabeth II/Royal Collection Trust

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Queen Elizabeth II will pass Queen Victoria as Britain’s longest-serving monarch on Sept. 9. Read our coverage here.

About a year ago, the royal household realized it had a problem. In September 2015, Queen Elizabeth II would pass her great-great grandmother, Queen Victoria, as the longest-reigning monarch in Britain (as well as in Canada and 14 other realms). However, no one was sure when that historic moment would occur. Dates ranging from Sept. 9 to Sept. 11 were posited. The calculations themselves give different results, depending on whether days alone are counted; or years and days; or years, months and days.

So, to be definite, the bibliographer at Windsor Castle sat down with historical records and did some rather precise mathematical calculations to settle the arguments once and for all. (My stories on the subject are here and here.)

Maclean’s was given two pages of annotated calculations by the royal press office, with the proviso that they would not be published until just before the big day. Here are the royal computations, along with a few value-added snippets from Maclean’s:


queen all 2Queen Victoria’s reign

Queen Victoria came to the throne on the death of her uncle, King William IVqueen logo, on June 20, 1837. She recorded in her diaryqueen logo that it was reported to her that his death had taken place at “12 minutes past 2 this morning.”

Her reign ended at her own death, on Jan. 22, 1901. In the official bulletin, the time as given as 6:30 in the evening, although the Duke of Argyll (husband of her daughter Princess Louisequeen logo), who doubtless had insider information, states in his biography of the Queen, VRIqueen logo: Her Life and Empire, p. 389, that she died at “6:35 in the evening.”

This was a reign of 63 years, 7 months, 2 days, 16 hours, and 23 minutes.

However, because both years and months vary in length, the less ambiguous measure is to calculate the total in days, hours and minutes. This takes into consideration the years that were leap years (remember that 1900 was not a leap year, unlike 2000), and the lengths of the various months between June and December. On this calculation, she reigned 23,226 days, 16 hours and 23 minutes.queen logo

This consists of:

  • June 21 to Dec. 31, 1837: 194 days
  • 1838 to 1900, i.e., 63 calendar years of 365 days plus 15 leap days: 23,010 days
  • Jan. 1 to 21, 1901: 21 days
  • Remaining hours of Jun. 20, 1837 (21 hours, 48 minutes) and majority of hours of Jan. 22, 1901 (18 hours, 35 minutes) = 1 day plus 16 hours 23 minutes

Total: 23,226 days, 16 hours, 23 minutes

The current reign

Her Majesty came to the thronequeen logo on the death of her father, King George VI, on Feb. 6, 1952.queen logo The exact time of his death is not known: He was seen at his bedroom window around midnight on Feb. 5, and is thought to have died in the very early hours of Feb. 6 in his sleep (so exact minutes become somewhat academic in the calculation).

Assuming the time was around 1 a.m. that morning, the Queen will (God willing) pass her great-great grandmother’s record around 5:30 in the evening of Sept. 9, 2015queen logo, again calculating number of days.

This consists of:

  • Feb. 7 to Dec. 31, 1952 (including the leap day): 329 days
  • 1953 to 2014, i.e., 62 calendar years of 365 days plus 15 leap days: 22,645 days
  • Jan. 1 to Sept. 8 [2015]: 251 days
  • Remaining hours of Feb. 6, 1952 (23 hours approximately) and majority of hours of Sept. 9, 2015 (17 hours, 30 minutes) = 1 day, 16 hours, 30 minutes approximately

Total: 23,226 days, 16 hours, 30 minutes approximately

N.B. If the calculation is expressed as 63 years, seven months, two days and 16.5 hours, there is a different result, of the milestone being passed on the evening of Sept. 8, 2015, because this ignores the different length of February and June only half cancelled out by the leap day in 1952.

The third possible way of calculation is to reckon it as 63 years, i.e., to the exact anniversary, and then 216 days, 16-and-a-half hours after that, which results in the milestone being passed on the evening of Sept. 10, 2015, because it ignores the fact that the Queen has had 16 leap days in her reign, not Queen Victoria’s 15. Calculating by the number of the days is the way that avoids these pitfalls or equivocations.