During your German studies, you have come across the letter ‘ß’ which your German teacher calls SZ or sharp S. The letter was introduced in 1903 because the double S in Roman typography looked similar to SZ in old German typography. It fell out of use in Switzerland but is still used in Standard German typography to this day. For a long time ß existed only as a lower-case letter, but a capital version has since been introduced. ß stands after long vowels and diphthongs and, contrary to popular belief, is not simply replaceable with double S. You may also have wondered how to type ß on your computer when writing up your homework for your German language course: on an Apple Mac computer, hold down the S-Key on your keyboard and select 1, same applies to iOS. On a Windows computer, hold down the ALT key and type 225.
When is it ß and when is it ss?
The rule is simpler than most learners expect. When the vowel before the sharp s-sound is short, you write a double s. When the vowel is long, or when there is a diphthong, you write ß.
Short vowel, so double s: dass, der Fluss, lassen, fassen
Long vowel or diphthong, so ß: das Maß, die Straße, heißen, weiß
Can I just replace ß with ss?
Students often ask in lessons whether they can simply write ss instead of ß. The answer is nein: in Standard German the two spellings are not interchangeable, and swapping one for the other changes the word. The one exception is Swiss German, where ß does not exist at all and is always replaced by ss.
How to type ß
On a Mac, an iPhone or an Android phone, hold down the s key and ß appears as an option above it. Slide across to choose it. On a Mac you can also press Option and S together, which is quicker once you are used to it.
On a Windows PC, hold down Alt and type 0223 on the numeric keypad, with Num Lock switched on. On a laptop without a numeric keypad, the simplest route is to add the German keyboard layout, which gives ß a key of its own next to the 0.
What about a capital ß?
A capital version does exist. The Council for German Orthography admitted ẞ into the official spelling rules in June 2017, so both STRASSE and STRAẞE are now correct. SS remains the usual choice and the one most readers expect. Holding down a capital S offers ẞ in the same way on a Mac or a phone. On Windows, hold Alt and type 7838.
Want to get these details right from the start? Private German lessons in London cover spelling and pronunciation alongside everything else.