Calvin

This name is sometimes used—and sometimes mistaken—as a variant of Kelvin.
https://www.behindthename.com/name/kelvin

Also Dutch: https://www.meertens.knaw.nl/nvb/naam/is/Calvin

I know of two baby boys named Calvin born just recently...one of them happens to be my grandson!

In 2018, 53 is the most common age for an American (U.S.) Calvin who is registered male with the Social Security Administration. It is the 373rd most common male first name for living U.S. citizens.