Thelda vs Theo
American parents have registered 39,333 Theos since 1880, against 521 Theldas. Theo is still ahead, with 3,966 babies in 2025.
Babies given each name, 1880–2025
Thelda Theo
Each line is every baby given the name that year, girls and boys added together — the only count that means the same thing for both names. A line breaks where the name fell below five babies in a year — the point at which the SSA stops publishing it — rather than being drawn through a figure nobody published. A single published year in a gap shows as a dot.
Who was ahead
Theo has been the commoner name in every year either was published, 1880 to 2025. The lead has never changed hands.
The closest they came was 1935, when Thelda had 24 and Theo had 110.
Side by side
| Thelda | Theo | |
|---|---|---|
| Total US births | 521 | 39,333 |
| Most in one year | 32 | 4,182 |
| Babies in 2025 | under 5 | 3,966 |
| Estimated living today | 100 | 33,000 |
| Median age today | 82 | 4 |
| Peak year | 1926 | 2023 |
| Best rank | 1,414th girls | 78th boys |
| Rank in 2025 | unranked | 82nd |
| First recorded | 1902 | 1880 |
| Girls / boys | 521 / 0 | 3,503 / 35,830 |
A rank is a position within one sex’s list for one year, so the two rank rows are not subtracted from one another and the winning column is not marked on them. The living figure is a life-table estimate, not a count.
Which name is older
Half of the Theldas alive today are over 82; half the Theos are over 4. That is 78 years between them: two names in use at the same time, worn by two different generations.
Compare something else
Related comparisons
Social Security Administration birth records, 1880–2025, public domain. Full histories: Thelda and Theo.