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 came out of fashion in Switzerland but is still used in Standard German typography to this day. ß did not exist as a capital letter, but a capital ß was recently introduced. ß stands after long vowels and diphthongs and, contrary to belief, is not simply replaceable with double S. You may have wondered how to type ß on your computer when typing 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.
Want to get these details right from the start? Private German lessons in London cover spelling and pronunciation alongside everything else.