Fionn has been given to about 682 people in the United States since 1880. It was most common in 2018, which makes it a current name.
Its best year was 2018, when 40 babies were given the name, ranking 2964th. The typical living American called Fionn is about 12 years old today.
Source: US Social Security Administration, national and state name files, 2025 release, and the Office for National Statistics for England and Wales. Etymology researched and written by our editors. Living-population and median-age figures are our own estimates, described in the methodology.