Spellings
Caius or Kaius?
In the US in 2025, 54% of babies in this name family were spelled Caius and 46% Kaius. Same name, slightly different impression: here are the figures for each spelling.
Ten years ago
Caius already led in 2015, with 56% of the family's births; it has 54% in 2025. All spellings together, the family went from 248 to 470 births (+90%).
| Spelling | 2015 | 2025 | Change |
|---|---|---|---|
| Caius | 138 | 254 | +84% |
| Kaius | 110 | 216 | +96% |
How they sound
All of these spellings are said the same way: /ˈkaɪəs/ (KYE-us). So the choice is about how it looks: it is the spelling people will read on a birth card, a name tag or an email address, and the one your child will sometimes spell out.
In France
None of these spellings is given in France often enough to be counted.
Sources: Social Security Administration (SSA), Insee (France), 2025 data. How we calculate these figures.
Which spelling is yours?
The one-minute style quiz.