Sydnei has been given to about 635 people in the United States since 1880. It was most common in 2005, which makes it a millennial-parent name.
Its best year was 2005, when 37 babies were given the name, ranking 3937th. The typical living American called Sydnei is about 23 years old today.
Source: US Social Security Administration, national and state name files, 2025 release. Etymology researched and written by our editors. Living-population and median-age figures are our own estimates, described in the methodology.