Amazon's preferred format for uploading files to Kindle is HTML. Word documents can easily be saved in HTML formatting, then uploaded to Kindle for file conversion. For best results, let your text speak for itself and do not try to over-control the formatting of your document. The appearance of your document will vary depending on the Kindle device each reader is using. Remember that few e-books are perfect in their formatting, including those on Kindle. Even best-selling books by top publishers are not perfectly formatted when transferred to Kindle.
Create a new document in Microsoft Word, 3.5 inches wide, 4 inches high, with 0.25 margins to emulate the size of the Kindle. This will let you see what your work will look like on a Kindle. When uploaded, Kindle will ignore the page size.
Open your original document in Microsoft Word. Copy and paste the contents of your book by pressing Ctrl-A on your keyboard, then Ctrl-C. Paste it into the new document by pressing Ctrl-V.
Change your font sizes to 10, 12, 14 and 18. These are the only sizes used by Kindle. Other font sizes will be converted to the size closest to one of those numbers. Font types will also be ignored by Kindle, so use Times New Roman to see what the fonts will look like on the Kindle while working on your document.
Format paragraphs to "Left Align." Remove any hyphens placed in the middle of words.
Use first-line paragraph indents as desired, not exceeding 1.5 inches. Kindle will automatically indent the first line of paragraphs, so you do not need to set these manually. Kindle will not recognise 0-indent first line formatting. For these paragraphs, use a first-line indent of 0.01 inches. Kindle will accept this, and it will not look like an indent to the reader.
Remove any tabs used in your document. Kindle will not recognise them.
Remove any tables from your document. Kindle will be unable to format them correctly.
Use page breaks as desired. Place a page break before every chapter.
Insert hyperlinks to the Internet as desired.
Use Word's Table of Contents feature to create a table of contents with links to each chapter. Then format the table of contents and delete all page numbers. Page numbers will vary depending on the font size selected by the reader, as well as the device being used to read the document.
Save the document as with HTML formatting by selecting "Save as..." and selecting HTML in the formatting options.
Review your document thoroughly before uploading to Kindle. Use Word to make changes to your document. If you need to make changes to the HTML code, do not use Word, as this will produce unpredictable results in your document. Use Notepad or an HTML editing software to edit HTML code.