Theory
#6,091 in 2025UnisexGirls' nameBoys' nameMeaning not yet documented
Theory has been given to 257 babies in the U.S. since 2006. In 2025 it ranked #6,091 of 17,293 girls’ names in use. Its peak year was 2023, with 20 recorded. It's used for both sexes: 64% girls, 36% boys all-time.
Babies named Theory, 2025
1 in 166,000
Theory over time, 1880–2025
Based on births in the U.S. Babies given the name each year. Hover the chart — or focus it and use the arrow keys — for any year. Gaps mean the name was given fewer than 5 times that year; these counts are unpublished.
Girls or boys — Theory over time
In 2025, Theory went to 67% girls and 33% boys.
A sex is only published in years it reached five applications, so a stretch at 0% or 100% means the other side stayed under that floor — not that it was never used.
How common is Theory?
Everything below is computed from the 2025 data — the most recent year available.
- Among all babies, 2025
- 1 in 166,000
- 20 of 3,315,165 births
- Among girls only
- 1 in 80,400
- <0.01% of girls
- Rank, 2025
- #6,091
- of 17,293 girls’ names in use
- Coin-flip room size
- 114,896 kids
- Even odds of a second one
Where Theory sits on the popularity scale
Chance at least one other child shares the name
If the other children were drawn at random from the 2025 national name distribution. Real classrooms cluster by region and community, so treat these as a floor, not a ceiling.
Put another way: gather 114,896 children born in 2025 and it's an even bet that one of them is another Theory. In a class of 30 the chance is Under 1%.
When Theorys were born
Half of everyone ever recorded as Theory was born before 2021 — so the typical Theory is around 4 today.
- Biggest decade
- 2020s
- 60.6% of all use
- Born in the last 25 years
- 100.0%
- A modern name
- Recorded since 1950
- 165
- People you could plausibly meet
2020s — 60.6% of all recorded uses (100).
Is Theory rising or falling?
Rank movement and count movement can disagree — the number of distinct names in use keeps growing, so a name holding a steady count still slides down the list. Both are shown.
- Rank vs 1 year ago
- +1,137
- Places climbed
- Rank vs 5 years ago
- +5,956
- Places climbed
- Rank vs 10 years ago
- +8,276
- Places climbed
- Births vs 10 years ago
- 2.86×
- More babies than then
- Share of its own peak
- 100.0%
- Peak was 2023 (20)
- Years since peak
- 2
- Years
- Year-to-year steadiness
- Shifting
- 24.9% average annual change
Spellings of Theory
Theory is not the most common spelling — Sherry is, with 64.3% against Theory's 0.05%.
Grouped by closeness of spelling (up to two letter changes), same sex, with a floor on all-time use. It catches Sophia/Sofia and Aiden/Ayden, and misses spellings that sound alike but look different, like Sean and Shawn.
Theory by the numbers
The raw record for each sex the name is used for.
As a girl's name
Names similar to Theory
Matched on shared beginnings and endings, similar length, and comparable popularity.
Sibling names for Theory
Names from the same era and popularity tier — the two things that make a sibling set feel deliberate — skipping lookalike spellings and shared initials.