Guillermo
Masculine · “will”
Guillermo is overwhelmingly a boys’ name — 32,074 boys against 74 girls since 1880.
Guillermo is the Spanish William: the same early Germanic name that spread across medieval Europe, reshaped by Castilian into three syllables that lean on the middle one, with the double-l softening into a y. It has been on US records for well over a century without ever spiking or fading — the kind of name that arrives with grandparents, uncles and a ready-made nickname already attached.
How old is the name Guillermo?
Guillermo first appears in US birth records in 1885 — 140 years ago. The typical Guillermo alive today was born around 1992, making them about 33 years old. About 28,000 people named Guillermo are estimated to be alive in the US today.
When was the name Guillermo most popular?
Guillermo peaked in 1996, reaching #352 nationally. Today it ranks #901, 549 places below that high. See the whole 1996 chart.
Where it comes from
From Willahelm to Guillermo
The story of Guillermo
The name began as the Frankish Willahelm, one of the most successful compounds in early Germanic naming, and traveled through Old French as Guillaume. From there it crossed the Pyrenees into the Iberian languages, taking a different shape in each: Guillem in Catalan, Guilherme in Portuguese, Guillermo in Castilian. It was worn by counts, bishops and kings across medieval Spain and Aragon, and later carried to the Americas, where it has been a standard Spanish given name for centuries. Its arrival in US records tracks the long presence of Spanish-speaking families in Texas, California and Florida — never a fashion, always in use.
Meaning
will, desire + helmet, protection
From the Germanic elements wil (will, desire) and helm (helmet, protection) — the same pair behind William, Wilhelm and Guillaume.
How the name formed
- Willahelm
- Wilhelm
- Guillaume
- Guillem
- Guillermo
Related forms: William · Guillaume · Guilherme · Guillem · Guglielmo · Wilhelm
Pronouncing Guillermo
gee-YEHR-moh
Hard g as in get; the ll is a y sound, not an l. English speakers often land on gih-YAIR-mo, which is close enough to pass unremarked.
Nicknames for Guillermo
High
What the data says
146 years of official birth records
The long climb, and where it stands now
The same years in position rather than babies
- First recorded
- 1885
- Most boys named
- 1992659 — the highest on record
- Peak rank
- #352reached in 1996
- Change vs 2022
- −8.0%264 in 2025, from 287
Rank is a position, a count is a headcount, and they move independently — a name can hold its rank while the number of babies behind it falls. Source: U.S. Social Security Administration.
Guillermo in other languages
The same name elsewhere
- William in English — same name
- Guillaume in French — same name
- Guilherme in Portuguese — same name
- Guillem in Catalan — same name
- Guglielmo in Italian — same name
- Wilhelm in German — same name
Strongest US states over the last decade: Texas, California, Florida.
Guillermos among us
people named Guillermo are estimated to be alive in the US today
About 1 boy in 6,470 born in 2025 was named Guillermo
Estimated from SSA birth records and published actuarial life tables. Method
Is it right for you
What happens to a name after it peaks
The Damion test
Every popular name lives one long story — a climb, a peak, a slow settling back. Guillermo's later chapters haven't been written yet, so we borrowed them: Damion climbed just as high around 1977, and its whole arc is on record. Line the two peaks up, and Damion's path sketches the road Guillermo is walking now.
Guillermo sits in the calm middle of the cycle — neither chasing a wave nor sliding off one. Middle-of-the-cycle names age slowly and predictably.
A scored estimate from 146 years of naming cycles — not a prophecy. Great names outlive statistics. How this is scored
Where Guillermo is headed
Guillermo should hold steady through 2030 — the curve is flat, and flat curves are the most predictable kind.
High confidence — fitted on official counts through 2025.
A damped-trend projection of the official birth data — a sketch of momentum, not a promise. Every name's forecast, ranked.
Guillermo beside its neighbors
The names ranked closest to Guillermo in 2025, in babies rather than position — the bars are to scale.
US boys given each name in 2025.
The trade-off
- Two well-established short forms, Memo and Guille, both in real everyday use rather than invented for convenience.
- Has an exact counterpart in most European languages — William, Guillaume, Guilherme, Wilhelm — so it translates rather than needing explanation.
- A documented record stretching back to the early Middle Ages, with no gap in use since.
- Spelling is fixed and standard in Spanish; no competing variants to choose between.
- English speakers who have not seen it before will reach for a hard L or a silent u. Most Guillermos spend some years correcting it, then stop minding.
- The English cousin, William, is far more common in the US, so the name may get quietly flattened to Will or Willy in school and at work — welcome to some families, less so to others.
- It is a distinctly Spanish form, which is part of its appeal and also means it sits noticeably in an otherwise English-language sibling set.
Nobody names a baby alone.
Put Guillermo to the vote.
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What they receive
Someone added a name to your list
Guillermo
Masculine · #901 in the U.S.
Frequently asked
- How many Guillermos are there in the world?
- No country counts the world's names, so there is no worldwide figure — anyone quoting one is estimating. About 28,000 people named Guillermo are estimated to be alive in the US today.
- How popular is the name Guillermo in 2025?
- Guillermo ranks #901 among US boy names in 2025, with 264 babies given the name.
- How rare is the name Guillermo?
- About 1 in every 6,470 US boys born in 2025 was named Guillermo — 264 in all.
- Will my child share the name Guillermo with classmates?
- Guillermo will almost certainly be the only one in school.
Ranked beside Guillermo
Names sitting at a similar level of popularity right now.
Foster#901 · Kael#903 · Nael#903 · Kannon#903 · Alistair#897 · Kaleo#897 · Marcello#897 · Lucien#897
Looking for what else is popular rather than what resembles Guillermo? See the current top 100.
Choosing between Guillermo and another name?
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US figures from the Social Security Administration. 1880–2025. Data & methodology
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