Recorded 1947–2025 · United States
Sydni was most popular in 2000, when 468 American babies were given the name — ranking #1,040 that year. In 2025 it ranked #18,449, with 8 births. Across 1880–2025 the Social Security Administration has recorded 5,361 people named Sydni.
Sydni first appears in Social Security Administration records in 1947, which makes it about 78 years old as a recorded American name. It has been recorded in 49 of the 79 years since.
The Social Security Administration has recorded 5,361 American births named Sydni between 1880 and 2025. That is recorded US births, not a world population — it counts people issued a Social Security number at birth in the United States. Of those, roughly 5,291 are estimated to be alive today.
8 American babies were named Sydni in 2025, ranking #18,449 that year.
Sydni is falling. Across 2021–2025 it averaged 12 births a year, against 64 a year across 2011–2015 — a change of -81% over the decade.
Measured on recorded births. American births overall have fallen since 2007, so most established names lose births over any recent decade — a name can shed births and still hold its rank. Compare the rank above, which is measured against the other names of the same year.
Across the whole record Sydni is a girl’s name — 100.0% of the 5,361 Americans given it were girls and 0.0% were boys. In births since 2016 it is 100% girls and 0% boys.
Counted from every US birth the Social Security Administration recorded under this name, so it reflects use rather than opinion. A name given to fewer than five babies of one sex in a year is withheld at source and is not counted.
Roughly 5,291 Americans named Sydni are alive today — 99% of everyone ever recorded with the name. The median is 25 years old, and half are between 21 and 29. That is a narrow band: Sydni arrived and faded within about a decade rather than staying in steady use.
An estimate, not a count. Recorded births are carried forward through the Social Security Administration’s 2023 period life table, by age and sex. That table describes mortality in one recent year, so it credits the oldest cohorts with today’s survival rather than the harsher rates they actually lived through — the further back a name peaked, the more this will overstate how many remain. It counts people issued a Social Security number at birth, not immigrants who arrived later.
How much more common the name is in each state than across the country as a whole.
See Sydni on the interactive charts
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Source: U.S.A. Social Security Administration. Years 1880–2025. namelegacy.org