Last name Koestlin (Koestlin 
) , around the globe, is a rare surname. The cognomen Koestlin is habitual in Germany, where it is a rare surname, Australia, where it is a very rare surname, and Canada, where it is an extremely rare surname. In absolute terms, it is commonest in Germany, Australia, and the United States.
| VARIANT | COUNTRY |
|---|---|
| Koestlin | Australia, United States, Germany, Canada |
| friedrich koestlin (b. 1749) |
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| friedrich koestlin (b. 1845) |
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| marie koestlin (b. 1856) |
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| rudolf koestlin (b. 1908) |
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