Recorded 1885–2025 · United States
Guillermo was most popular in 1998, when 693 American babies were given the name — ranking #762 that year. In 2025 it ranked #1,848, with 264 births. Across 1880–2025 the Social Security Administration has recorded 32,148 people named Guillermo.
Guillermo first appears in Social Security Administration records in 1885, which makes it about 140 years old as a recorded American name. It has been recorded in 125 of the 141 years since.
The Social Security Administration has recorded 32,148 American births named Guillermo 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 28,139 are estimated to be alive today.
264 American babies were named Guillermo in 2025, ranking #1,848 that year.
Guillermo is holding steady. Across 2021–2025 it averaged 289 births a year, against 383 a year across 2011–2015 — a change of -25% 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 Guillermo is a boy’s name — 0.2% of the 32,148 Americans given it were girls and 99.8% were boys. In births since 2016 it is 0% girls and 100% 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 28,139 Americans named Guillermo are alive today — 88% of everyone ever recorded with the name. The median is 31 years old, and half are between 20 and 45.
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 Guillermo on the interactive charts
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Source: U.S.A. Social Security Administration. Years 1880–2025. namelegacy.org