Longest-reigning popes

Pope Pius IX, the pope with the longest verifiable reign

The longest papal reigns of those whose reign lengths can be determined from contemporary historical data are the following:

1. Saint Peter (c. 30–64/68): c. 34 – c. 38 years (Around 12,000–14,000 days)^[234]
2. Bl. Pius IX (1846–1878): 31 years, 7 months and 23 days (11,560 days)
3. St. John Paul II (1978–2005): 26 years, 5 months and 18 days (9,665 days)
4. Leo XIII (1878–1903): 25 years, 5 months and 1 day (9,281 days)
5. Pius VI (1775–1799): 24 years, 6 months and 15 days (8,962 days)
6. Adrian I (772–795): 23 years, 10 months and 25 days (8,729 days)
7. Pius VII (1800–1823): 23 years, 5 months and 7 days (8,560 days)
8. Alexander III (1159–1181): 21 years, 11 months and 24 days (8,029 days)
9. St. Sylvester I (314–335): 21 years, 11 months and 1 day (8,005 days)
10. St. Leo I (440–461): 21 years, 1 month, and 13 days (7,713 days)