Convert 8 to 18

[Migel]

Please.

How can I read AC 8 file wit AC 18?

[mikas]

You don't say your OS or OS version.

But still, you can check it all out from here:

https://community.graphisoft.com/t5/Setup-License-articles/Archicad-file-and-protection-compatibilit...

and download the necessary converters from here:

https://graphisoft.com/downloads/fileconverter

On a Mac it's more complicated than on Win because of (un)compatible OS versions you might need.

[Karl Ottenstein]

As mikas showed - you can open an AC 8.1 file without any problems (other than missing library parts if the file is not a PLA).  Hopefully, your file is an 8.1 file rather than 8.0 (8.0 was a super buggy version that was quickly replaced with 8.1) so that it should just open.

If you need the file converter, then using a Windows machine (or borrowing one from someone temporarily) is the only solution  - unless you have an ancient Mac with a 32 bit OS laying around.