Although you may have no trouble understanding what you write, this doesn't mean that your target readers have the same level of comprehension. If you know your audience, you have an idea of how simple or complex your writing style should be, however this can be tricky to track as you write. Word 2013's spell check has a feature that can analyze your documents for readability, so you can assess if you have created an intelligible document pitched at the right reading level.
Enable Readability Features
Word doesn't automatically show readability statistics, so you must enable them before you can check reading levels in documents. In Word, open "File" and then "Options." In the Word Options window, select "Proofing." Check the "Check Grammar with spelling" and "Show readability statistics" boxes and click "OK" to apply the changes.
Check a Document's Reading Level
Open the Word document you want to check. Select the "Review" tab and then "Spelling & Grammar" or press the "F7" key on your keyboard. If your document has no typos, you'll go straight to the Readability Statistics summary window. If you have errors to correct, complete the spell check first. Look in the Readability area of the summary window to find the Flesch-Kincaid grade for the document -- this is your reading level.
Analyze Your Reading Level
The Flesch-Kincaid level gives your document a benchmark reading ability score based on grade school levels. So, if your document scores a 5, a 5th grader will be able to understand its content. Although your target level may vary depending on your audience, Microsoft recommends that documents should ideally fall between scores of 7 and 8. You may also find the Flesch reading ease summary useful. This analyzes how easy a document is to read on a scale to 100 -- the higher your score, the better.