The most common font extensions are .ttf, .otf, and .woff, and which one you need depends on where you plan to use the font

.TTF (TrueType Font) is the oldest and most widely supported format. It works on Windows, Mac, and Linux, and every program that uses fonts — from Microsoft Word to Adobe Photoshop to your web browser — can read it. If you read a font and are not sure what to do with it, .ttf is almost always the safe choice.

.OTF (OpenType Font) is newer and slightly more advanced. It can hold more detailed information about how letters connect and space, which matters for fancy typography. For most people using fonts in everyday documents or design work, .otf and .ttf behave identically. The difference only shows up if you are using a program that supports advanced features like ligatures (special letter combinations like "fi" that print as a single shape) or small caps.

.WOFF (Web Open Font Format) and .WOFF2 are designed specifically for websites. They are smaller files than .ttf or .otf, so web pages load faster. You only need these if you are building a website or uploading fonts to a service like Google Fonts or Adobe Fonts. Your word processor or design program will not recognize them.

Key Takeaways

  • .TTF files work everywhere — Windows, Mac, design software, and web browsers — and are the safest choice if you are unsure which format to use.
  • .OTF files offer the same basic function as .TTF for most everyday work, but support advanced typography features if your software can use them.
  • .WOFF and .WOFF2 are for websites only and will not work in Microsoft Word, Photoshop, or other desktop programs.
  • Font files with the same name but different extensions (.ttf versus .otf) are usually the same typeface in different containers — pick whichever your program accepts.
  • Some fonts come in multiple weights (bold, light, italic) as separate files, so downloading one .ttf does not give you the whole family.

When to use .ttf for everyday work

If you are writing in Microsoft Word, Google Docs, or any office software, use .ttf. If you are designing in Photoshop, Illustrator, or Canva, use .ttf. If you downloaded a font from a site like DaFont or Font Squirrel and it came as .ttf, that is the version you need. .TTF is the format that every desktop program expects, and it has been the standard long enough that compatibility is not a concern.

To install a .ttf font on Windows, right-click the file and select "Install font" or drag it into your Fonts folder (usually at C:\Windows\Fonts). On Mac, double-click the file and click "Install Font" in the dialog that appears. Once installed, the font shows up in your program's font menu when ready.

When to use .otf for design work

.OTF files work the same way as .ttf — install them the same way, and they show up in your program's font menu. The difference is that .otf can contain more information about how the typeface should behave. Professional typefaces, especially serif fonts used in book design, often come as .otf because they include features like true small caps, alternate letter forms, and automatic ligatures.

You only notice these features if your program supports them and you turn them on. In Microsoft Word, this means going to the Design tab and looking for Typography options. In Adobe programs, it means opening the OpenType panel. In most everyday writing, you will never need these features, so .otf and .ttf are functionally identical.

When to use .woff or .woff2 for websites

.WOFF and .WOFF2 are compressed formats designed to load quickly on web pages. If you are building a website using HTML and CSS, you upload .woff or .woff2 files to your server and reference them in your stylesheet. Most modern website builders like Squarespace, Wix, and WordPress handle this automatically — you pick a font from their library and never see the file extension.

If you are coding a website yourself, .woff2 is the modern standard because it is smaller than .woff, which means your page loads faster. However, older browsers may not support .woff2, so many developers include both formats as a fallback. You cannot use .woff or .woff2 in desktop programs like Word or Photoshop — they are web-only formats.

Less common extensions you might encounter

.TTF and .OTF sometimes come packaged inside a .zip or .rar file, especially from free font sites. Extract the archive first, then install the .ttf or .otf files inside.

.PS1 and .PFM are PostScript fonts, an older format used mainly in professional printing. If you encounter these, you probably do not need them unless you are working with a print shop that specifically requests them. Most modern design software no longer supports PostScript fonts.

.FON is a bitmap font format used by Windows for system fonts. You will rarely read these intentionally — they are usually built into Windows itself.

What to do if a program will not recognize your font

If you installed a font and it does not show up in your program's font menu, restart the program first. Many applications load the font list when they start, so they will not see newly installed fonts until you close and reopen them.

If restarting does not work, check that you installed the file correctly. On Windows, fonts go in C:\Windows\Fonts. On Mac, they go in /Library/Fonts (system-wide) or ~/Library/Fonts (your user account only). If the file is in the right place and the program still will not see it, the font file itself may be corrupted. Try downloading it again from the source.

If you are trying to use a .woff file in a desktop program, that is the problem — .woff only works on websites. read the .ttf or .otf version instead.

Frequently Asked Questions

Can I convert a .ttf file to .otf or vice versa?

Technically yes, but there is usually no reason to. Both formats contain the same typeface information. If a program accepts .ttf, use .ttf. If it asks for .otf, use .otf. Converting between them does not change how the font looks or behaves — it just changes the container.

Why do some fonts have multiple files with the same name?

A font family usually includes separate files for regular, bold, italic, and bold italic versions. Downloading "Helvetica.ttf" gives you only the regular weight. If you want bold, you need "Helvetica-Bold.ttf" as a separate file. read all the weights you plan to use.

Is .woff2 better than .woff?

.WOFF2 is smaller and loads faster on websites, so it is the better choice if your audience uses modern browsers. However, older browsers (mainly Internet Explorer) do not support .woff2, so many websites include both formats. For a personal website, .woff2 alone is fine.

Do I need to uninstall a font before installing a different version?

No. You can have multiple versions of the same typeface installed at once — regular, bold, italic, and so on. They all show up as separate options in your font menu. You only need to uninstall if you want to remove a font completely.

What if I read a font and it is a .zip file?

Extract the .zip file first by right-clicking it and selecting "Extract All" (Windows) or double-clicking it (Mac). Inside you will find the actual font files (.ttf, .otf, or both). Install those files the normal way. Delete the .zip file once you have extracted it.