How to Insert a Horizontal Line Under a Heading in Word

To add a line beneath a heading in Microsoft Word, click in the heading paragraph, then choose Home > Paragraph > Borders > Bottom Border. This adds a divider that follows the paragraph as you edit the document. You can also draw a line shape or use Word’s automatic horizontal-line shortcut, but a paragraph border is usually the neatest, easiest-to-maintain choice. The steps below are for Microsoft 365 on Windows, with Mac notes where the controls differ.

What You’ll Need

A document open in Microsoft Word for Microsoft 365. The ribbon labels may look slightly different in older Word versions.
The heading under which you want the line. If possible, format it with a built-in heading style, such as Heading 1 or Heading 2, so it remains consistent with the rest of your document.
A moment to decide whether you want a line attached to the heading paragraph or a freely positioned line. Use a paragraph border for a divider that should move with text; use a shape if you need exact placement or a shorter line.

Step-by-Step

Find and select the heading paragraph. Scroll to the heading and click anywhere in its text. You usually do not need to highlight the words: Word applies a paragraph border to the paragraph containing the insertion point. If the heading is on its own line, clicking within that line is enough. Avoid clicking in the paragraph below it, or the border may appear in the wrong place.
Open the Borders menu. On Windows, select the Home tab and find the Paragraph group. Locate the Borders button, which is usually shown as a small square grid or border icon. Select the small arrow beside it to open the menu. If the ribbon is simplified or the window is narrow, expand the ribbon or widen the Word window to make the Paragraph controls easier to find.
Apply a bottom border. In the Borders menu, select Bottom Border. Word draws a line along the bottom edge of the heading paragraph. In many documents, the border runs across the paragraph area rather than stopping at the last letter of the heading. That full-width divider is normal and often looks more balanced than a line that ends at the text.
Check the result in the document. Click elsewhere or use the arrow keys to leave the heading, then look at the spacing and line position. The border should sit just below the heading, above the next paragraph. If it appears above the heading or beneath a different paragraph, undo the change with Ctrl+Z on Windows and repeat the step with the insertion point in the correct paragraph.
Adjust the heading spacing if needed. A border can look crowded if the heading has very little space below it. Select the heading paragraph and use Home > Paragraph dialog launcher to open the Paragraph settings. Adjust Spacing After to add space between the heading and the following text. This changes paragraph spacing, not the border’s line thickness. Preview the result at normal page size so the divider does not seem detached from the heading.
Change the line’s appearance only if necessary. Open the Borders menu again and choose Borders and Shading if that option is available in your Word build. In the dialog, select a border style, color, or width, make sure only the bottom edge is selected in the preview, and set Apply to to Paragraph. Confirm the choice. If the dialog is not shown in your version, the basic Bottom Border is still a reliable option; avoid repeatedly clicking border icons because some clicks toggle borders on or off.
Save and review the page. Save with Ctrl+S on Windows, then check the heading and the paragraph after it. If the divider is near a page break, use Print Layout or print preview to confirm that the heading and line appear together where you expect. A paragraph border is part of the paragraph formatting, so it will usually travel with the heading if text above it changes.

On a Mac: Click in the heading, open the Home tab, and use the Borders menu in the Paragraph area to choose Bottom Border. The ribbon arrangement can differ by Word version and window size, but the command works on the selected paragraph in the same way. Mac undo is Command+Z, and save is Command+S.

To draw a separate line instead: Choose Insert > Shapes > Line, then drag below the heading. Hold Shift while dragging to keep the line horizontal. Select the line to open Shape Format, where you can change its outline color or weight. Shapes offer more placement control, but they can shift or overlap text when the page layout changes, so they are less suitable for a divider that must stay attached to a heading.

Common Mistakes

Applying the border to the wrong paragraph. Word treats a border as paragraph formatting, not as decoration attached only to the heading’s letters. If the cursor is in the paragraph below, the line may appear under that paragraph instead. Click directly in the heading and check the result before continuing.
Choosing all borders instead of Bottom Border. The Borders menu contains several options. Selecting outside or all borders can create a box around the heading rather than a single line below it. If that happens, use Ctrl+Z on Windows or Command+Z on Mac, reopen the menu, and choose only Bottom Border.
Using underscores or repeated hyphens to draw the line. Typing a long row of underscore characters may look like a divider, but it is ordinary text. It can wrap, change length when the font changes, and be read aloud as punctuation by assistive technology. Use a paragraph border for a document divider instead.
Expecting a paragraph border to end at the heading text. A bottom border generally spans the paragraph’s available width, even if the heading contains only a few words. If you specifically need a short line, use a shape and position it deliberately, or place the heading and divider in a layout designed for that purpose.
Adding a shape without checking its wrapping and position. A line shape may be anchored to a paragraph and can move when text is edited. If it crosses another line or jumps after an edit, select it and review its layout or wrapping options. For a simple separator, replacing the shape with a paragraph border is often the quickest fix.

Tips

Use heading styles for repeatable formatting. If you want the same divider below every Heading 2, modify the Heading 2 style rather than adding a border manually to each heading. In the Styles area, right-click the style, choose Modify, then use the Format controls to open the Borders settings. Check that the bottom border is applied to the paragraph, and confirm the change. Menu wording and dialog placement can vary slightly between Word versions.
Keep heading and divider together. If a heading is stranded at the bottom of a page, select it and open the Paragraph dialog. Under Line and Page Breaks, enable Keep with next so the heading stays with the paragraph that follows. This setting is useful for readability; it does not itself add or change the border.
Use a consistent line weight and color. A thin, neutral rule usually works well for a section divider. Strong colors or heavy rules can make a document feel crowded. If you customize the border, check it both on screen and in a PDF or print preview, particularly if the document will be printed in grayscale.
Remember that formatting can be copied. Once one heading has the appearance you want, use Format Painter to apply formatting to another paragraph. Because paragraph borders are included in paragraph formatting, check that the target heading’s alignment and spacing remain appropriate after copying.
Use the automatic line shortcut only when you want its behavior. In a blank paragraph, type three hyphens and press Enter. If Word’s AutoFormat feature is enabled, it may convert the characters into a horizontal paragraph border. This is quick, but the resulting rule is still paragraph formatting, not a drawn line. Undo immediately if Word inserts a rule where you did not intend one.

Troubleshooting

The line does not appear. Confirm that the cursor is in the heading paragraph, then reopen the Borders menu and select Bottom Border. If the document uses a theme or a very light border color, the line may be difficult to see. Open Borders and Shading and choose a visible color and width. Also check that you have not selected a border command that removes the existing border.

The line appears in the wrong place. Undo once, click inside the correct heading paragraph, and apply Bottom Border again. If the heading and the next sentence are actually part of the same paragraph because a manual line break was used, Word may treat them as one paragraph. Place the cursor in the correct paragraph or create a separate paragraph where appropriate before applying the border.

The line surrounds the heading or appears above it. Open the Borders menu and choose No Border to clear the unwanted paragraph border. Then apply Bottom Border only. If you used Borders and Shading, inspect the preview box and make sure the bottom edge is the only edge enabled.

The line is too close to the heading or the text below. Adjust the paragraph spacing around the heading rather than inserting blank lines or adding spaces. Blank paragraphs can create awkward gaps and may separate the heading from its divider when the layout changes. Use the Paragraph settings to make a measured spacing adjustment, then review the surrounding text.

The rule is too long or moves when editing. A paragraph border spans the paragraph width by design. If you need a short, precisely placed line, insert a line shape instead and review its wrapping and anchoring. If the shape moves after edits, adjust its layout options or switch to a border if exact length is not essential.

The three-hyphen shortcut does nothing. Word’s automatic border feature may be disabled, or the characters may have been typed into a paragraph that already contains text. Use the Borders menu to add the line directly. If you want to change AutoFormat behavior, look in Word’s AutoCorrect or AutoFormat settings; the exact location varies by Windows or Mac version.

Frequently Asked Questions

Does a bottom border go under the heading text or across the page?
A paragraph bottom border usually extends across the available width of the paragraph, not just beneath the letters. Indents and paragraph layout affect where it begins and ends. Use a line shape if the rule must be shorter than the paragraph width.

Can I add a line under every heading of the same level?
Yes. Modify the relevant heading style and add a bottom border to that style’s paragraph formatting. Headings using that style will receive the same divider, and future headings in the style will match. Review the result after changing a style because the formatting may affect every paragraph that uses it.

Will the line stay with the heading if I add or remove text?
Usually, yes. A paragraph border belongs to the heading paragraph, so it moves with that paragraph as the document reflows. A drawn line shape is a separate object and may need its position or anchor adjusted after edits.

How do I remove the line?
Click in the heading paragraph, open Home > Paragraph > Borders, and choose No Border or toggle off the bottom border, depending on the menu shown. If you just added it, Undo is another option. Removing the border does not delete the heading text.

Can I use a keyboard shortcut to add the line?
Word does not use one universal default keyboard shortcut for applying a bottom paragraph border. The three-hyphen-and-Enter AutoFormat method may work if that feature is enabled. For a predictable result, use the Borders menu and select Bottom Border.

What is the best method for a professional document?
For most reports, proposals, and notes, a bottom paragraph border is the cleanest choice because it stays attached to the heading and does not require manual positioning. Choose a shape only when you need a line of a specific length or placement that paragraph borders cannot provide.

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