Sadao is a very rare variant of Sadie that was most common in the 1920s and has all but disappeared.
Sadao is a boy name. It last appears in U.S. records in 1934. Sadao first appears in 1914 and peaked in 1926 (22 births).
| Year | U.S. births | U.S. + territories | Rank |
|---|---|---|---|
| 1934 | 7 | — | #3,232 |
| 1933 | 11 | — | #2,349 |
| 1931 | 7 | — | #3,350 |
| 1930 | 11 | — | #2,578 |
| 1929 | 15 | — | #2,082 |
| 1928 | 10 | — | #2,815 |
| 1927 | 8 | — | #3,405 |
| 1926 | 22 | — | #1,650 |
| 1925 | 14 | — | #2,303 |
| 1924 | 13 | — | #2,452 |
| 1923 | 12 | — | #2,586 |
| 1922 | 21 | — | #1,751 |
| 1921 | 15 | — | #2,249 |
| 1920 | 10 | — | #2,931 |
| 1919 | 15 | — | #2,135 |
| 1918 | 14 | — | #2,243 |
| 1917 | 12 | — | #2,400 |
| 1916 | 15 | — | #2,025 |
| 1915 | 7 | — | #3,349 |
| 1914 | 5 | — | #3,678 |