No doubt that you’ve probably seen a css font-family declaration that didn’t include a specific webfont, but just the
sans-serif fallback, or values like
All of those values will return the operating system’s default sans-serif font, with some differences:
-apple-systemworks only for newer MacOS versions (El Capitan and newer) and iOS
BlinkMacSystemFontworks only for older Mac OS versions (Yosemite and older)
system-uiworks for all operating systems, but there’s one notable exception: it doesn’t work in the Firefox browser. Firefox doesn’t support this value, so your text will be displayed in the default fallback which is a serif font
sans-serifwill work in all browsers and operating systems, but should be only used as fallback, because in some cases operating systems have quirks like different sans font set for web than in its interface
Whether you use a custom font or not, the recommended complete css font-family declaration is:
font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Ubuntu, "Helvetica Neue", Oxygen, Cantarell, sans-serif;
You can safely omit Oxygen and Cantarell since they are targeted to certain Linux versions only.
Roboto, Ubuntu, sans-serif will be ok for Linux distros.
Default sans-serif font in MacOS
MacOS (El Capitan and newer)
MacOS (older versions)
Default sans-serif font in Windows
The difference between Microsoft Sans Serif and MS Sans Serif is that MS Sans Serif was a bitmap/raster font available in 8, 10, 12, 14, 18, and 24 sizes and Microsoft Sans Serif is a TrueType scalable font.
MS Sans Serif was based on Helvetica and in all versions up to Windows 3.1 it was called Helv.
Windows (Vista and newer, including Windows 10)
Microsoft Sans Serif
Windows (95, NT, Millennium)
MS Sans Serif
Windows (older versions including Windows 3)
Default sans-serif font in Linux
Many Linux users re-configure defaults to other fonts like Inter UI or others. So it’s almost impossible to accurately mention defaults, except for the Ubuntu distro which has its own font as default. Red Hat also has commissioned its own fonts, Red Hat Display and Red Hat Text.
Other distros (Arch Linux, Debian, Fedora etc.)
It varies, can be DejaVu Sans, Noto Sans, Liberation Sans etc.
Default sans-serif font in iOS
iOS (9 and newer)
iOS (8 and older)
Default sans-serif font in watchOS
San Francisco Compact
Default sans-serif font in Android
Android (4.0 )
Android (older versions)