Counting words sounds like a simple task but it is not.
In fact there are several different ways to do it — and that’s why different computer programs come up with different results for the task of counting words.
For example is “can’t” one word or two? How about “it’s” or “take-out”? Depending on what you decide to count as a word, you will get different word counts.
Word counts can easily vary by 10% depending on how how a "word" is defined.
So if your text is counted as 500 in AutoCrit and 550 in Microsoft Word, don’t worry. Each word processing program is making internally consistent decisions about how to analyze your text.