calibre Line Spacing Wrong After Conversion: How to Fix It

When calibre line spacing looks wrong after conversion, the cause is usually one of four things: a conversion setting changed the book’s layout, the source document contains restrictive CSS, the reading app is overriding the converted file, or automatic cleanup altered the paragraph structure. The visible result may be crowded lines, excessive line height, large gaps between paragraphs, missing paragraph indents, double indentation, or blank lines that appear only on a particular device.

The safest approach is to identify whether the problem is inside the converted book or limited to the viewer before changing multiple settings. This guide focuses on spacing and layout rather than font size. It also explains what a successful fix should look like, so you know when to stop troubleshooting.

1. Confirm the Symptom With a Small Safe Test

Begin with one affected book and preserve its original format. calibre normally keeps the original file you added, but you should still avoid deleting formats, replacing library folders, or running bulk conversions while diagnosing the problem.

1.1 Identify Which Type of Spacing Is Wrong

Open the converted book and decide which symptom you actually see:

• Lines within the same paragraph are too close together or too far apart.
• Paragraphs have unusually large vertical gaps.
• Blank lines appear between every paragraph.
• Paragraph gaps disappeared and first-line indents appeared instead.
• Paragraphs have both vertical gaps and first-line indents.
• Only headings, block quotes, lists, or footnotes have bad spacing.
• The book looks correct in calibre but wrong on the target device.

This distinction matters because line height, paragraph margins, text indentation, and empty paragraphs are controlled separately. Changing the line-height setting will not reliably remove blank paragraphs, while removing paragraph spacing will not correct tightly packed lines inside a paragraph.

1.2 Compare the Source and Converted Formats

Open the source format and the converted format in calibre’s viewer. Examine the same chapter and paragraph in both. Then, if possible, test the converted file in the actual reading app or device where it will be used.

If the source already has the problem, conversion is probably preserving poor source formatting. If the source looks correct but the output is wrong in every reader, investigate conversion options and output CSS. If the output looks correct in calibre but wrong on one device, focus on that device’s layout controls and format support.

Success at this stage means you can state exactly where the problem begins. Stop changing settings until you know whether the issue is in the source, conversion output, calibre viewer, Content server viewer, or target reader.

2. Check the Conversion Settings That Control Spacing

Select the affected book, choose Convert books, and inspect the settings for that individual title. calibre can save conversion options for each book, so a setting used during an earlier conversion may return even if your global defaults are different.

2.1 Reset the Line Height Setting

In the conversion dialog, open Look & feel and find the line-height controls. A direct line-height value sets spacing for elements that do not already define their own line height. It is a broad adjustment and can produce inconsistent results when some paragraphs have source-defined values and others do not.

For a neutral test, set the direct line-height option to its default or no-manipulation value. Also inspect the minimum line-height setting. A high minimum forces lines to remain widely spaced even when the source requests tighter spacing.

Convert the test book again and compare ordinary paragraphs, headings, lists, and notes. The fix is successful when normal body text has consistent vertical spacing without making headings or compact sections look unnaturally loose. If the result is correct, stop. Do not add Extra CSS merely to duplicate the same rule.

2.2 Review Paragraph Spacing Options

The Remove spacing between paragraphs option does more than close vertical gaps. It can also apply a first-line indent, producing a traditional print-style layout. This is useful when the source separates paragraphs with margins, but it can look wrong when the book already uses indents or relies on blank lines for scene breaks.

Turn this option off if paragraphs unexpectedly lost their vertical separation, gained indents, or became double-indented. Turn it on only if you intentionally want paragraphs separated primarily by indentation rather than vertical space. If an indent-size field is available with the option, check that it is not larger than intended.

Also look for an option that inserts blank lines between paragraphs. Disable it when conversion has added regular gaps throughout the book. Inserted blank lines and source paragraph margins can combine, making each paragraph appear to have twice the expected space.

Success means body paragraphs follow one clear convention: either modest spacing between paragraphs or a first-line indent, unless the source design intentionally uses both. Scene breaks should remain visibly distinct.

2.3 Check Saved Settings Before Changing Global Defaults

If only one or two books are affected, do not begin by changing calibre’s global conversion preferences. Open the individual conversion dialog and restore its options to defaults, then reconvert the book.

If a clean individual conversion works, the cause was probably a stored book-specific option. This also explains why reinstalling calibre often fails to resolve layout problems: the relevant conversion choices may be associated with the book or reproduced from the same source.

Metadata such as title, author, series, and cover normally does not control paragraph spacing. Downloading metadata again is therefore not a meaningful fix for this symptom. Likewise, email delivery and the Content server generally transport an existing format rather than rewriting its paragraph CSS. Investigate those features only if they are delivering a different format from the one you tested.

3. Inspect Source CSS, Extra CSS, and Automatic Processing

When basic conversion settings are neutral but the layout remains wrong, the book’s HTML and CSS are the next likely cause. EPUB, AZW3, and similar reflowable formats use CSS properties such as line-height, margin-top, margin-bottom, and text-indent to control spacing.

3.1 Remove or Correct Extra CSS

Open the conversion dialog and inspect Extra CSS. Rules entered here are appended to the styles derived from the source, making them capable of overriding much of the original presentation.

Temporarily remove custom spacing rules, especially broad declarations targeting every paragraph or the entire document. Common sources of trouble include fixed line heights, large paragraph margins, and universal indentation rules. Convert again without Extra CSS.

If the spacing becomes normal, add back only the rule you actually need. For example, a narrowly targeted rule for body paragraphs is safer than applying the same declaration to paragraphs, lists, headings, block quotes, and footnotes. Avoid using aggressive priority overrides unless you have inspected the competing styles.

Success means the intended paragraph style is corrected without altering headings, lists, captions, or special sections. Stop once the narrow rule produces a consistent result.

3.2 Disable Heuristic Processing for the Test

Heuristic processing attempts to repair poorly formatted source documents by recognizing patterns. It can be useful for files with hard line breaks or inconsistent structure, but pattern-based changes can also misidentify deliberate spacing and scene breaks.

Disable heuristic processing and reconvert the same source. Pay particular attention to paragraphs that were merged, split, or surrounded by new blank space. If disabling heuristics fixes the book, leave the feature off unless you can identify a specific sub-option that the source genuinely needs.

Success means paragraph boundaries match the source’s logical structure and intentional scene breaks remain intact. Do not enable every heuristic option as a general cleanup step.

3.3 Inspect the Book With Edit Book

For EPUB, AZW3, and other editable formats supported by calibre’s editor, right-click the converted book and choose Edit book. Open a chapter containing the spacing problem and use the preview, Inspector, or Live CSS panel to see which rules apply to the affected paragraph.

Look for these properties:

• line-height for spacing between lines in the same element.
• margin-top and margin-bottom for gaps between blocks.
• text-indent for first-line indentation.
• padding on paragraphs or surrounding containers.
• Empty paragraph elements or repeated line-break elements creating visible blank lines.
• Inline style attributes that override the main stylesheet.

The Live CSS panel is particularly useful because it shows matching and inherited rules as well as the final calculated values. A crossed-out rule has been superseded, so editing that rule alone may have no visible effect.

If every paragraph contains a fixed inline line height, changing a general stylesheet rule may not be enough. If empty paragraph elements are responsible for the gaps, adjusting line height will not remove them. Make one carefully targeted change, save a copy, and run the editor’s checking tools before testing again.

Success means the corrected CSS applies to all intended paragraphs and the book passes its internal checks without creating new structural errors.

4. Rule Out Viewer and Device Overrides

A converted book can contain correct spacing while a reader displays something different. Many reading applications allow users to override publisher formatting, paragraph alignment, margins, or line spacing.

4.1 Test in the Target Reader

Transfer the exact output file you tested in calibre. Confirm the filename, format, and modification time so that an older copy is not being opened from the device or reading app.

In the reader’s appearance settings, reset line spacing, paragraph spacing, margins, and publisher-style overrides to neutral values. Some readers offer only a few spacing presets rather than precise controls. In that case, test the middle or default preset first.

If the device displays EPUB and AZW3 differently, test the format designed for that reader instead of repeatedly forcing CSS changes into an unsuitable output. Reader limitations can affect which style properties are honored.

Success means the same transferred file has acceptable spacing in the intended reading environment. Once that happens, stop modifying the conversion settings even if another viewer renders the book slightly differently.

4.2 Check calibre Viewer and Content Server Styles

calibre’s desktop viewer supports a stylesheet that can be applied across books. A custom viewer rule may make every title appear too loose, too tight, or over-indented even though the files themselves are correct. Review the viewer’s preferences and temporarily clear custom Styles before testing.

The Content server also has its own browser-based viewer and reading preferences. If spacing is wrong only when using Read in the server, reset that viewer’s appearance controls and compare the downloaded file in another reader.

A firewall, antivirus tool, email account, or server network option is unlikely to alter line spacing inside a successfully delivered file. Those areas are relevant when transfer fails, a file is blocked, or the wrong format is delivered, not when the correct file opens with a CSS layout problem.

4.3 Verify the File Actually Reached the Device

If the device continues showing the old layout, remove only the device’s copy of the test book, safely disconnect it, reconnect it, and send the corrected format again. Verify that the reader is not opening a cloud-synced duplicate.

On devices that expose USB connection modes, ensure the storage mode used by calibre allows normal file transfer. Operating system permissions, antivirus, and cloud synchronization matter when calibre cannot replace the file or when another service restores an older copy. They do not normally rewrite CSS by themselves.

Success means the device opens the newly converted file and the displayed layout matches the corrected test.

5. Use Conversion Logs and Debug Output

If the visible settings look correct but the result remains wrong, inspect what calibre actually used during conversion rather than relying on memory.

5.1 Read the Conversion Job Details

Open the Jobs panel after the conversion finishes and double-click the completed conversion job. The detailed log records the options used and may reveal a saved line-height value, paragraph-spacing option, heuristic setting, input plugin, or output profile you did not expect.

Compare the log from a bad conversion with one from a clean test. If the settings differ, change the specific option responsible and repeat the test. A normal completion message does not prove that the layout is correct, because undesirable CSS can be processed successfully.

5.2 Generate Conversion Debug Output

Use the conversion dialog’s debug option to save the stages of calibre’s conversion pipeline to a temporary folder. The generated folders let you compare the source-derived HTML with later processed output.

• Inspect the input stage to see what the input plugin extracted from the source.
• Inspect the parsed or structure stages to identify changes made during preprocessing.
• Inspect the processed stage to see the CSS immediately before output generation.

If bad margins or line heights are already present in the input stage, the source document is responsible. If they appear later, a conversion transform or option introduced them. If all debug stages look reasonable but the device is wrong, return to reader overrides and format support.

5.3 Use calibre-debug Only When Needed

Most spacing problems do not require command-line tools. If a plugin, custom workflow, or unexplained application behavior is suspected, start calibre in debug mode with calibre-debug -g and reproduce the conversion. This can expose plugin errors or unexpected processing messages.

Temporarily disable third-party plugins that participate in import, conversion, or post-conversion processing, then repeat the controlled test. Plugins unrelated to conversion are unlikely to affect line spacing.

Success means the same source converts correctly when the suspected plugin or custom step is absent. At that point, leave the plugin disabled and consult its documentation rather than changing unrelated calibre settings.

6. Run a Clean Temporary Test Before Reinstalling

Reinstalling calibre is rarely the best first response to a spacing issue because the problem is commonly stored in the source, the book’s conversion options, or the reader’s preferences. A temporary test provides clearer evidence with less risk.

1. Copy one legal, DRM-free source file to a temporary local folder.
2. Add it as a separate test entry without deleting the existing library record.
3. Restore the individual conversion settings to defaults.
4. Leave Extra CSS empty and heuristic processing disabled.
5. Convert to the intended output format.
6. Open the result in calibre and the target reader.
7. Change only one spacing-related option if the problem remains.

Keep the test folder outside cloud-synchronized locations while troubleshooting. Cloud tools can lock files, delay replacements, or restore an older copy, which makes results difficult to interpret. You do not need to move or delete your main calibre library.

If the clean conversion works, compare its job log and CSS with the affected book. If it fails only with one source file, source quality is the likely cause. PDF sources deserve special caution because fixed page layouts do not always convert cleanly into reflowable paragraphs. Visual gaps in a PDF may become empty paragraphs, line breaks, or separate positioned text fragments.

Success means you can reproduce either a correct conversion or the same failure with a minimal set of settings. That evidence is more useful than reinstalling, deleting the library, or changing multiple preferences simultaneously.

7. Quick Fix Checklist

• Compare the source and output at the same paragraph.
• Test the output in calibre and the intended reader.
• Reset the direct line-height setting to its neutral value.
• Check whether the minimum line height is forcing wide spacing.
• Disable inserted blank lines between paragraphs.
• Review Remove spacing between paragraphs and its indent size.
• Restore the book’s saved conversion settings to defaults.
• Temporarily remove Extra CSS.
• Disable heuristic processing for the control conversion.
• Inspect line height, margins, indentation, and empty elements in Edit book.
• Clear custom styles in calibre’s viewer when only that viewer is wrong.
• Reset spacing overrides in the target reading device or app.
• Confirm the newly converted file replaced the older device copy.
• Read the completed conversion job log.
• Use debug pipeline output if the responsible conversion stage is unclear.

8. Frequently Asked Questions

8.1 Why did removing paragraph spacing add indents?

The option is intended to create a print-like paragraph layout. Removing vertical separation commonly goes together with adding a first-line indent so readers can still identify paragraph boundaries. Turn the option off or reduce its associated indent setting if that is not the design you want.

8.2 Why does changing line height have no effect?

The source may define its own line height on paragraphs or inline elements. A general conversion value may apply only where no value already exists. Inspect the calculated styles in Edit book, or temporarily filter or override the specific source property after confirming which selector controls it.

8.3 Why are there blank lines even with paragraph spacing removed?

The gaps may come from empty paragraph elements, repeated line breaks, container padding, or explicit margins rather than calibre’s paragraph-spacing option. Inspect the HTML and CSS around one affected location before making another global conversion change.

8.4 Why is the book correct in calibre but wrong on my device?

The device may apply its own line-spacing preset, ignore part of the book’s CSS, use an older transferred copy, or render the chosen format differently. Reset the device’s appearance settings and verify that the corrected output file was actually transferred.

8.5 Should I convert the output format again to fix it?

Repeated conversion can accumulate formatting changes and make diagnosis harder. Return to the best available source format and perform a clean conversion with controlled settings. Keep intermediate converted files only for comparison.

8.6 Is calibre not working if only one book has bad spacing?

Probably not. A single affected title usually points to source CSS, saved per-book conversion settings, structural problems, or reader behavior. Treat it as a book-specific conversion issue unless a clean test shows the same symptom across unrelated sources.