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Overleaf font sizes are set in LaTeX, not in a menu: there are three separate controls, and picking the right one is most of the job. The base size goes in the \documentclass options (10pt if you give none), ten size commands change a passage relative to that base, and the extsizes classes cover base sizes outside the standard options. This guide starts with which control to use for each job.
What font sizes are used for in research writing
In theses, articles, posters and handouts, size changes are used for small-print material such as footnotes and table text, for emphasis in headings, and for meeting a venue’s base-size requirement. Journal and university templates often fix the base size for you, so the practical question is usually how to change one passage without touching the rest. For where Overleaf fits among research writing tools, see what Overleaf is and writing in LaTeX collaboratively on Overleaf.
Which control sets the font size?
| You want to | Use | Scope |
|---|---|---|
| Set the size of the whole document | A size option in \documentclass, for example [12pt] |
Every size command is then relative to this base |
| Change one word, sentence or block | A size command inside braces, for example {\small ...} |
Only the text inside the braces |
| Change everything from a point onward | A size command used as a switch, without braces | From that point to the end of the document unless another switch is used |
| Use a base size outside the standard options | An extsizes class such as extarticle |
Whole document, base size from 8 to 20pt |
Install or access
The size commands are part of the LaTeX document classes, so nothing needs installing in Overleaf: open a project at overleaf.com and type the commands in the source. The extsizes classes are published on CTAN as the extsizes package (version 1.4a, LPPL license, checked 2026-10-29), which provides extarticle, extreport, extletter, extbook and extproc.
Step by step: change font size in Overleaf
1. Set the base size for the whole document
- Find the first line of your main
.texfile, the\documentclassstatement. - Add the size in square brackets, for example
\documentclass[12pt, letterpaper]{article}. - Recompile. Overleaf’s documentation names 9pt, 11pt and 12pt as other options, and states that if none is specified the default size is 10pt.
2. Change the size of one passage
Overleaf lists these size commands from smallest to largest:
\tiny, \scriptsize, \footnotesize, \small, \normalsize, \large, \Large, \LARGE, \huge, \Huge
Put the command and the text inside braces so the change stays local:
Normal text, {\huge huge text}, and normal text again.3. Change the size from a point onward
A command used without braces works as a switch. Overleaf’s documentation states: “A switch changes the style from this point to the end of the document unless another switch is used.” Use \normalsize to return to the base size.
Output and how to read it
The size commands are relative, not absolute. Overleaf’s documentation states that “the actual size is not absolute but relative to the font size declared in the documentclass statement.” The practical consequence is that changing the base option from 10pt to 12pt rescales every command at once, so a \small passage in a 12pt document is larger than a \small passage in a 10pt document. Choose the base size first, then adjust passages.
Font families: overleaf font and overleaf fonts
Switch between serif, sans serif and typewriter
Family commands come in two forms. The command form takes the text as an argument and the declaration form is a switch: \textrm / \rmfamily for serif, \textsf / \sffamily for sans serif, and \texttt / \ttfamily for typewriter. To make a family the document default, Overleaf shows \renewcommand{\familydefault}{\sfdefault} (or \rmdefault).
Use a different typeface
Overleaf’s typeface page shows \fontfamily{qcr}\selectfont setting the TeX Gyre Cursor typeface for the text it applies to, and it notes that not all fonts are available on Overleaf. A typeface can be changed for a specific element rather than the whole document.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| A size change spreads to text after the passage | A size command without braces is a switch that lasts to the end of the document unless another switch is used | Wrap the passage in braces, or finish with \normalsize |
Sizes look different after editing \documentclass |
Commands are relative to the size declared in \documentclass |
Re-check the passages that use size commands after changing the base |
| The document is 10pt when you expected another size | 10pt is the default when no size is given | Add the size option to \documentclass |
| You need a base size beyond the standard options | The extsizes classes provide base sizes of 8 to 20pt | Use an extsizes class such as extarticle |
Alternatives for sizes outside the standard options
| Approach | What it changes | Source |
|---|---|---|
Size option in \documentclass |
The base size of the whole document (default 10pt) | Overleaf: Creating a document in LaTeX |
Size commands (\small to \Huge) |
A passage, relative to the base size | Overleaf: Font sizes, families, and styles |
extsizes classes |
The base size, from 8 to 20pt | CTAN: extsizes |
For figures, see how to insert a figure in LaTeX; for equations, see starting a new line in a LaTeX equation.
FAQ
What is the default font size in Overleaf?
10pt, when no size is given in the \documentclass statement. Overleaf’s documentation names 9pt, 11pt and 12pt as other options.
How do I change the font size of one part of an Overleaf document?
Put a size command and the text inside braces, for example {\small smaller text}. Only the text in the braces changes.
Are the size commands fixed point sizes?
No. They are relative to the size declared in \documentclass.
How do I use a base size larger than 12pt or smaller than 9pt?
Use one of the extsizes classes (extarticle, extreport, extletter, extbook or extproc), which CTAN describes as providing documents with a base font size from 8 to 20pt.
How do I change the font in Overleaf?
Use the family commands (\textrm, \textsf, \texttt or their switch forms), or select a typeface with \fontfamily{...}\selectfont. Not all fonts are available on Overleaf.
Sources
- Overleaf: Font sizes, families, and styles (checked 2026-10-29)
- Overleaf: Creating a document in LaTeX (checked 2026-10-29)
- Overleaf: Font typefaces (checked 2026-10-29)
- CTAN: extsizes (checked 2026-10-29)
