Spacing between paragraphs is a related consideration. This comes from the days of creating a manuscript on a monospaced typewriter (five spaces was about one-half inch) and from the half-inch automatic tab stops made popular by the first word processing software. Microsoft Word's default indentation is set to 0.5 inches. E.g., with 15-pts leading, indent no more than 15-pts indentation, or 0.21 inches. Indent no more than the leading (space between lines within a paragraph). Visually, 12-pt Helvetica is quite different than 12-pt Times New Roman, so you might want to make adjustments based on the visual appearance. E.g., if you’re using a 12-pt font, indent your paragraphs about 12 points, or 0.17 inches. If you choose to indent paragraphs (as opposed to setting them with a small space between each), set your indentation in as far as the font is high. If you use Microsoft Word, you'll have to create a new style for 'First Paragraph' and manually set all these ﬁrst paragraphs into that style. Don't indent the ﬁrst paragraph of a chapter or section.

Microsoft word change indent size