Cognomen Koolstra (Koolstra 
) , worldwide, is a rare surname. The last name Koolstra is characteristic of Netherlands, where it is quite a rare surname, Australia, where it is a very rare surname, and Canada. Measured by absolute frequency, the name is most common in Netherlands, the United States, and Indonesia.
| VARIANT | COUNTRY |
|---|---|
| Koolstra | Australia, United States, Indonesia, Netherlands, Canada |
| w. koolstra Dutch photographer, NL (b. 1862) |
|
|
| albertus koolstra (b. 1865) |
|
|
| meindert koolstra NL (b. 1917) |
|
|
| kirsten koolstra researcher (ORCID 0000-0002-7873-1511) |
|
|
| g. koolstra researcher ORCID ID = 0000-0002-6574-5789, US |
|
|
| jan harm koolstra researcher |
|