To test a document’s readability in Microsoft Word (Office 2007):
- Click the Microsoft Office Button, and then click Word Options.
- Click Proofing.
- Make sure Check grammar with spelling is selected.
- Under When correcting grammar in Word, select the Show readability statistics check box
To test a document’s readability in Microsoft Word (Office 2010 and later):
- Click the File tab, and then click Options.
- Click Proofing.
- Under When correcting spelling and grammar in Word, make sure the Check grammar with spelling check box is selected.
- Select Show readability statistics.
Source: Microsoft Office