How about this?

!k:: ;Hotkey is Alt+K
Loop 1500
{
Send +{Right}
}
Send {Esc}
Return

The problem with this script is that it will also count spaces and tags as characters.

I'm sure experienced coders can come up with something more elegant.

I think it’s fine as a general all-purpose script.

It can be tuned for specific applications, like Word, Excel, PowerPoint…

Thank you Nora,

It works with plain text, but unfortunately not with tables. Probably I should describe why I need this. For example, I have a 2-column export docx that I have to divide in equal parts between several translators. Now I just select and copy some portion of text (roughly) from the export file and paste it into a new document to know how many chars are in there. Ideally, I want a script to count and select cells based on the not-greater-than-1500-chars condition. In case anybody knows how to do that, I would really appreciate your sharing this sacred knowledge. So far I will use the script from Nora, it is definitely better then what I have now (=nothing). Thank you again 

.

Even though I admit the work should be paid and it is fair, but I am not sure if this is a good idea of doing business here on an SDL resource. If you are serious, email me.

 .

krupa adrian, I need the script to select cells containing not more than 150/1500/15000/whatever characters, rather than split them. I don't want you to spend your precious time on what is not needed. Don't bother to make the "merge" code or whatever you call it. Just forget it. Thank you