# What does "overfull hbox" mean? (Why is there a black mark at the end of a line?)

I often see output from TeX with the warning overfull hbox, badness 10000. What does this message mean?

• they are "seeding" which means asking and answering their own questions to build a nice bedrock of "good" questions so that newbies to the site will have good examples. Jul 26, 2010 at 19:48
• Aye! The whole point of the private beta is to seed answers to questions that we anticipate may be common. Answering your own question is perfectly acceptable if you have a good answer but no one has bothered to ask the question yet. Jul 26, 2010 at 20:18
• Yes, but! Please do give some time before answering so that others have a chance as well. This also has the effect of producing novel answers which you might have not known otherwise! meta.tex.stackexchange.com/questions/4/… Jul 28, 2010 at 16:45
• Possible duplicate of What are underfull hboxes and vboxes and how can I get rid of them? Jul 28, 2016 at 21:49
• How can this be a duplicate of a question about underfull boxes? Jul 28, 2016 at 23:15

Quoting Phil Miller answer, for completeness:

This message means that a line of your document is too long to fit within the horizontal space on the page, and TeX couldn't find a good way to break it apart. This will usually result in text hanging out past the margin, possibly even running off the side of the page. Common causes are long words without proper hyphenation information and long displayed equations.

These warnings can also happen by manually breaking works with - as commented by Sebastian. This can be fixed by importing the package \usepackage{hyphenat} and using its command \hyp{} to break words, i.e., hyphenated\hyp{}word instead of hyphenated-word. But as can be easily noted, typing \hyp{} all the time can be quite annoying. Here come in the babel package shorthands. See the question How to create an alternative to shortcut "= or \hyp{}?, to learn about the usage of the ~= shorthand. So you can write like hyphenated~=word, instead of hyphenated\hyp{}word.

Badboxes warnings can also be caused by breaking lines with \\ and \hbox as demonstrated on this other question: How to stop \newsavebox giving me bad boxes warnings or how to use better names with \setbox?

You can control how the overfull hbox, badness work configuring these latex parameters explained on:

1. badness is an integer from 0 to 10000 that is a measure of the quality of the spacing in any given box. https://en.wikibooks.org/wiki/TeX/definition/badness

2. \tolerance A parameter that tells TeX how much badness is allowable without error. [number] can range from 0 to 10000, and there are no units. https://en.wikibooks.org/wiki/TeX/tolerance

3. The TeX primitive \pretolerance is an integer parameter that is used in TeX's line breaking algorithm as described below. The quantity is an integer from -1 to 10000.

If \pretolerance is an integer from 0 to 10000, then TeX's line breaking algorithm first attempts to break up a paragraph without hyphenation. In this attempt TeX ties to minimize the badness of each line. If TeX can break up a paragraph so that none of the lines have badness greater than \pretolerance, then TeX accepts it. If this is not possible, TeX will re-attempt to break up the paragraph with the allowance of hyphenation of words. In this second attempt, the integer parameter \tolerance is used instead of \pretolerance. If TeX is unsuccessful in the second attempt an error is reported in the log file.

If \pretolerance is -1, then TeX bypasses the first attempt at breaking a paragraph without hyphenation. https://en.wikibooks.org/wiki/TeX/pretolerance

On these questions there are more related information about line breaking:

Hyphenation:

Miscellaneous:

1. underfull \vbox
2. What is the difference between \hspace*{\fill} and \hfill?
3. how to suppress "Underfull \vbox (badness 10000) ... while \output is active"?
4. http://www.tex.ac.uk/FAQ-overfull.html (La)TeX makes overfull lines
5. http://www.tex.ac.uk/FAQ-paraparam.html Why does it ignore paragraph parameters?

The first answer doesn't really help somebody fix the problem, though. Take a look at:

https://texfaq.org/FAQ-overfull

and

http://en.wikibooks.org/wiki/LaTeX/Text_Formatting#Hyphenation

to learn about \tolerance, \pretolerance, and \hyphenpenalty and how they affect the overfull/underfull behavior. Also, if you're fixing the document by hand, you can add hyphenation dictionary entries with \hyphenation or add discretionary hyphens into words with \-.

• Hyphenation was really it for me - as the word was not know and could not be auto-hyphenated and after adding a manual \- things were fine. Oct 29, 2019 at 19:53
• The first link is now dead. Jun 27, 2020 at 1:30
• Is there a way to show those boxes, as a red rectangular frame? Nov 23, 2020 at 18:53
• Thanks, \setlength{\emergencystretch}{3em} helped preventing overfull hbox highlighted with black boxes! :) May 31 at 19:54

This message means that a line of your document is too long to fit within the horizontal space on the page, and TeX couldn't find a good way to break it apart. This will usually result in text hanging out past the margin, possibly even running off the side of the page. Common causes are long words without proper hyphenation information and long displayed equations.

• If you use draft mode (\documentclass[draft]{article}) you can see black lines on the side of your document where there is overfull hbox badness. This is a convenient way to find and fix these errors.
– Otis
Jul 26, 2010 at 19:54
• @Otis: Or simply something like \overfullrule=1mm so that you don't get the unwanted side effects of the "draft" mode. Jul 26, 2010 at 20:34
• Overfull hboxes are not limited to overlong lines on a page. A hbox can overflow anywhere, for example, inside a table. Whithout \overfullrule in effect this is often hard to detect. Apr 17, 2011 at 5:06

I always like to see a visual example of these Latex messages. The images below show the most frequent occurrence of Overfull \hbox. So if you like visuals too, her you go: -> NOTE: The explanations above are very good, so don't miss out on them.

The Latex view:

The compiled pdf view:

The problem is, that sometimes Latex is not able to fit certain information in a defined space. As you can see here, the - overflows the right border which here causes the warning. Hope this helps!

Tip: you can visualize the borders, to simply see the problem locations, f.e. if the overlapping is not caused by text and no error message appears.

Use: \usepackage[showframe]{geometry}

• Welcome to TeX.SE! Please explain why this is a valid answer? I do not understand what you are meaning ... May 14, 2021 at 13:08
• @Mensch it seems to answer the question "what is an overfull hbox" with a visual example of an overfull hbox. It is not a complete MWE but it still shows the issue clearly I think. May 14, 2021 at 20:47
• @Mensch Thanks for your comment. I felt that it would be quicker to understand the underlying problem by seeing a visualization of it. I added some more explanation to make it more clear. May 15, 2021 at 16:31