Kai vs Kaius
American parents have registered 78,710 Kais since 1880, against 2,011 Kaiuses. Kai is still ahead, with 4,002 babies in 2025.
Babies given each name, 1880–2025
Kai Kaius
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
Kai has been the commoner name in every year either was published, 1926 to 2025. The lead has never changed hands.
The closest they came was 2025, when Kai had 4,002 and Kaius had 216.
Side by side
| Kai | Kaius | |
|---|---|---|
| Total US births | 78,710 | 2,011 |
| Most in one year | 5,732 | 216 |
| Babies in 2025 | 4,002 | 216 |
| Estimated living today | 78,000 | 2,000 |
| Median age today | 8 | 5 |
| Peak year | 2022 | 2025 |
| Best rank | 59th boys | 1,028th boys |
| Rank in 2025 | 93rd | 1,028th |
| First recorded | 1926 | 2005 |
| Girls / boys | 8,478 / 70,232 | 0 / 2,011 |
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 Kais alive today are over 8; half the Kaiuses are over 5. That is 3 years between them: two names in use at the same time, worn by two different generations.
Where each one is strongest
- Kai Hawaii (5.0×), Nevada (3.2×), Florida (2.3×)
- Kaius Arizona (2.6×), Washington (2.5×), Florida (2.5×)
How much commoner the name is in that state than it is nationally, from births recorded since 1910.
Both names abroad
Countries whose statistics office publishes both names, so the comparison can be made somewhere other than the United States.
| Country | Kai | Kaius |
|---|---|---|
| England and Wales | 25,329 | 280 |
| Scotland | 3,388 | 3 |
| Ireland | 1,870 | 4 |
Every spelling a country files separately is added together, over whatever years that country publishes — which is not the same range in any two of them, so read the columns against each other and not the rows.
Compare something else
Related comparisons
Social Security Administration birth records, 1880–2025, public domain. Full histories: Kai and Kaius.