Before, each and every Google Posts had the 100 to 300 word limit in your Google Posts. But recently Google has the 1,500 character limit for every Google Post. Well, Google will allow writing 1,500 characters on the Google post. This is an actual precise number and one of the interesting facts is that it will let all those writing for the Google posts know exactly when Google will cut them off. You can see that back in June there was 100-300 word limits but now, Google shows the 1,500 character limit. So, till now it will depend on how many characters you utilize on average for a word.
Forum discussion at Twitter.