Pope/Longest-reigning popes

== Longest-reigning popes ==
Although the average reign of the pope from the Middle Ages was a decade, a number of those whose reign lengths can be determined from contemporary historical data are the following:
# Pius IX (1846–1878): 31 years, 7 months and 23 days (11,560 days).
# John Paul II (1978–2005): 26 years, 5 months and 18 days (9,665 days).
# Leo XIII (1878–1903): 25 years, 5 months and 1 day (9,281 days).
# Pius VI (1775–1799): 24 years, 6 months and 15 days (8,962 days).
# Adrian I (772–795): 23 years, 10 months and 25 days (8,729 days).
# Pius VII (1800–1823): 23 years, 5 months and 7 days (8,560 days).
# Alexander III (1159–1181): 21 years, 11 months and 24 days (8,029 days).
# St. Sylvester I (314–335): 21 years, 11 months and 1 day (8,005 days).
# St. Leo I (440–461): 21 years, 1 month, and 13 days. (7,713 days).
# Urban VIII (1623–1644): 20 years, 11 months and 24 days (7,664 days).
Saint Peter is thought to have reigned for over thirty years (AD 29 – 64?/67?), but the exact length is not reliably known.