This is a list of prime ministers of Spain by time in office. The basis of the list is the inclusive number of days from being sworn in until leaving office.
Of the 102 prime ministers, only four served more than 10 years while sixty-six have served less than a year.
Francisco Franco, who also served as the Head of State until his death, is the only person to have served in the post of prime minister for more than two decades, ruling for a total of 35 years that were preceded by the coup of 1936 and the Spanish Civil War.
| Rank | Prime Minister | Length served | Terms | Party | Start |
|---|---|---|---|---|---|
| 1 | 35 years, 129 days | 1 | 1939 | ||
| 2 | 13 years, 175 days | 7 | 1871 | ||
| 3 | 13 years, 155 days | 4 | 1982 | ||
| 4 | 11 years, 290 days | 6 | 1874 | ||
| 5 | 8 years, 240 days | 7 | 1844 | ||
| 6 | 7 years, 349 days | 2 | 1996 | ||
| 7 | 7 years, 248 days | 2 | 2004 | ||
| 8 | Pedro Sánchez | (incumbent) | 3 | PSOE | 2018 |
| 9 | 6 years, 162 days | 2 | 2011 | ||
| 10 | 6 years, 137 days | 1 | 1923 | ||
| 11 | 5 years, 180 days | 4 | 1856 | ||
| 12 | 5 years, 152 days | 1 | 1826 | ||
| 13 | 5 years, 84 days | 5 | 1903 | ||
| 14 | 4 years, 236 days | 2 | 1976 | ||
| 15 | 3 years, 130 days | 3 | 1913 | ||
| 16 | 2 years, 293 days | 3 | 1837 | ||
| 17 | 2 years, 277 days | 1 | 1910 | ||
| 18 | 2 years, 243 days | 3 | 1912 | ||
| 19 | 2 years, 211 days | 2 | 1824 | ||
| 20 | 2 years, 185 days | 1 | 1973 | ||
| 21 | 2 years, 94 days | 2 | 1899 | ||
| 22 | 2 years, 49 days | 2 | 1931 | ||
| 23 | 1 year, 335 days | 1 | 1851 | ||
| 24 | 1 year, 318 days | 1 | 1937 | ||
| 25 | 1 year, 279 days | 1 | 1981 | ||
| 26 | 1 year, 224 days | 1 | 1838 | ||
| 27 | 1 year, 191 days | 3 | 1836 | ||
| 28 | 1 year, 166 days | 4 | 1868 | ||
| 29 | 1 year, 165 days | 2 | 1869 | ||
| 30 | 1 year, 150 days | 3 | 1933 | ||
| 31 | 1 year, 143 days | 1 | 1834 | ||
| 32 | 1 year, 135 days | 4 | 1917 | ||
| 33 | 1 year, 98 days | 2 | 1823 | ||
| 34 | 1 year, 51 days | 2 | 1840 | ||
| 35 | 1 year, 19 days | 1 | 1930 | ||
| 36 | José María Calatrava | 1 year, 4 days | 1 | 1836 | |
| 37 | 353 days | 2 | 1846 | ||
| 38 | 332 days | 3 | 1905 | ||
| 39 | 326 days | 1 | 1842 | ||
| 40 | 317 days | 2 | 1871 | ||
| 41 | 301 days | 1 | 1853 | ||
| 42 | 299 days | 2 | 1843 | ||
| 299 days | 2 | 1919 | |||
| 299 days | 1 | 1825 | |||
| 45 | 285 days | 2 | 1903 | ||
| 46 | 277 days | 1 | 1879 | ||
| 47 | 274 days | 1 | 1922 | ||
| 48 | 255 days | 1 | 1936 | ||
| 255 days | 1 | 1832 | |||
| 50 | 233 days | 1 | 1835 | ||
| 51 | 220 days | 3 | 1897 | ||
| 52 | 199 days | 1 | 1864 | ||
| 53 | 195 days | 1 | 1973 | ||
| 54 | Niceto Alcalá-Zamora | 183 days | 1 | 1931 | |
| 55 | 175 days | 1 | 1859 | ||
| 56 | 161 days | 1 | 1905 | ||
| 57 | 159 days | 1 | 1934 | ||
| 58 | 158 days | 1 | 1853 | ||
| 59 | 156 days | 1 | 1847 | ||
| 60 | 147 days | 1 | 1906 | ||
| 61 | 145 days | 1 | 1919 | ||
| 62 | 130 days | 2 | 1843 | ||
| 63 | 123 days | 1 | 1874 | ||
| 64 | 121 days | 1 | 1852 | ||
| 65 | 119 days | 1 | 1873 | ||
| 66 | 118 days | 1 | 1873 | ||
| 67 | 99 days | 1 | 1835 | ||
| 68 | 97 days | 1 | 1883 | ||
| 69 | 94 days | 1 | 1838 | ||
| 70 | 91 days | 1 | 1857 | ||
| 71 | 81 days | 1 | 1875 | ||
| 72 | 80 days | 1 | 1935 | ||
| 73 | 77 days | 1 | 1871 | ||
| 74 | 70 days | 2 | 1933 | ||
| 75 | 67 days | 1 | 1935 | ||
| 76 | 66 days | 1 | 1936 | ||
| 77 | 65 days | 1 | 1843 | ||
| 78 | 59 days | 1 | 1837 | ||
| 59 days | 1 | 1847 | |||
| 80 | 55 days | 1 | 1931 | ||
| 81 | 52 days | 1 | 1906 | ||
| 82 | 51 days | 1 | 1873 | ||
| 83 | 47 days | 1 | 1936 | ||
| 84 | 44 days | 1 | 1864 | ||
| 85 | 37 days | 1 | 1873 | ||
| 86 | 23 days | 1 | 1823 | ||
| 87 | 22 days | 1 | 1847 | ||
| 88 | 16 days | 1 | 1840 | ||
| 89 | 13 days | 1 | 1840 | ||
| 13 days | 1 | 1823 | |||
| 91 | 11 days | 1 | 1835 | ||
| 11 days | 1 | 1868 | |||
| 11 days | 1 | 1973 | |||
| 94 | 10 days | 1 | 1841 | ||
| 95 | 9 days | 1 | 1843 | ||
| 96 | 8 days | 1 | 1870 | ||
| 97 | 5 days | 1 | 1840 | ||
| 98 | 3 days | 1 | 1936 | ||
| 99 | 2 days | 1 | 1976 | ||
| 100 | 1 day | 1 | 1849 | ||
| 1 day | 1 | 1854 | |||
| 1 day | 1 | 1854 |