The German writing system does not specify the length, and consequently the quality, of vowels in the same unique way as the writing system of some other languages, for instance Hungarian, Czech, and largely also Dutch. On the other hand, it gives the reader a lot of hints. This article is an attempt to mould these hints into rules which can be applied by the learner. It turns out that few simple rules cover a good deal of all occurrences of vowels, but surprisingly much context has to be considered to be able to make reliable statements about most of the remaining ones.
The length of the vowels (and their quality: long vowels are different sounds from their short counterparts) is not always unambiguously deducible from the spelling. Roughly, the rules are, highest precedence first:
Vowels marked as long are long: <aa>, <ah>, <äh>,
<ee>, <eh>, <ie>, <ieh>, <ih>, <oo>,
<oh>, <öh>, <uh>, <üh>.
Examples:
Saal, sehr,
Bier, ihr,
Moos, Ähre.
Vowels followed by a geminated consonant (or <ck> or
<tz>) are short.
Examples: Kanne,
Tasse, schnell,
Zweck, Katze.
Vowels followed by more than one consonant are mostly short but with
quite some exceptions.
Examples: Kante,
halten, Hals,
Kopf; but long: Erde,
Trost, Obst.
Vowels followed by a single consonant or at the end of the word are
mostly long if and only if they are stressed, also with quite some
exceptions.
Examples (long):
Hefe,
gären,
Maschine,
Büro
Examples (short):
Hefe,
gären,
Maschine,
das,
bereit
When considering the consonants after a vowel, a consonant inserted in an inflexion does not count. For instance, when the stressed vowel <a> in the verb malen is long by the preceding rule, it is also long in the derived forms er malte and du malst.
On the other hand, there are word pairs by which it can be shown that there cannot be rules covering all cases. Compare Sucht–sucht, halte–malte, Busch–wusch, Most–Trost, quatschen–Latschen, Bus–Mus: in each of the pairs, the first word has a short stressed vowel, and the second, quite similarly spelt, has a long one.
By rules that are tailored to more specific situations, one can hope to resolve some of the remaining uncertainty how vowels are pronounced. In the remaining portion of this article we try to extract from the written form of a word as much information as possible about the pronunciation of the vowels in it. To this end, one has to consider how words are constructed, which is not always possible from the written form alone. In particular, one has to study word stress which is also a topic of quite some complexity. This article which started as an attempt to refine the simple rules above ended up in becoming an elaborate exposition of the German vowel system. A refined set of rules forms the last section of this article; the other sections contain the definition of the terms needed and glimpses on related issues.
Foreign words that have retained their foreign spelling and pronunciation (e.g. Engagement [,ãga:ʒ'mã:]) are not considered here; words of foreign origin are if they have been adopted to German phonology fully (e.g. Kartoffel [kar'tOf@l]) or at least to some degree (e.g. international [,?IntErnAtsjo'nA:l]).
In this article, we use a transliteration of the International Phonetic Alphabet in order that the article be readable even if the browser does not display IPA symbols correctly. By and large, we follow the suggestions of SAMPA and Kirshenbaum but we use also some characters of the ISO 8859-1 character set, in particular the letters Ø and ø in order to have a clear pairing of upper-case open and lower-case close vowels (except the two as), which is blurred in both ASCII-IPA schemes. As usual, the notions “open” and “close” are understood as relative to the graphically matching sound: an open [I] is opener (lower, more central) than a close [i] but not necessarily than each close vowel.
| IPA | i | ɪ | e | ɛ | ə | a | ɐ | ɑ | ɔ | o | ʊ | u | y | ʏ | ø | œ | ʔ | ç | ŋ | ʃ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| here | i | I | e | E | @ | a | 6 | A | O | o | U | u | y | Y | ø | Ø | ? | ç | N | S |
| SAMPA | i | I | e | E | @ | a | 6 | A | O | o | U | u | y | Y | 2 | 9 | ? | C | N | S |
| Kirshenbaum | i | I | e | E | @ | a | A | O | o | U | u | y | I. | Y | W | ? | C | N | S |
Phonetic notation is always included in square brackets, even though nearly always the phonemes are meant and not their phonetic realisation; this notation is also common in dictionaries. The notion of graphemes with angle brackets is used also for denoting digraphs, diphthongs, and other letter combinations that are below the morpheme level. Morphemes and words are denoted in green italics.
German pronunciation varies quite a lot across Germany even for speakers that take much effort in speaking clearly and distinctly. There is no region in Germany whose dialect has been declared standard. What comes closest to a German pronunciation standard is the work of Theodor Siebs (1862–1941) who published his “Deutsche Bühnenaussprache” (German stage pronunciation) in 1898, a work which has been continued until today. Initially designed for the stage, it has become a standard for the German language in general. Since the 1922 edition, the term “Hochsprache” (standard language) has been added to the title. In the book, it is emphasised that the requirements of the stage must not be taken as the basis of distinct and correct pronunciation elsewhere, lest it sound stilted and artificial. Unfortunately, they have not always followed their own advice and have included a number of features that sound very unnatural outside the stage, most notably the preference of the apical [r] over the uvular [R] and the reluctance to allow a vocalised [6] for an <r> at the end of a syllable. Particularly with this feature, following the standard (or, equivalently, the phonetic examples in this article) may yield an exaggerated and unnatural pronunciation.
The “reine Hochlautung” (pure standard pronunciation) as defined in Siebs's book is rather narrow in that hardly any speaker will adhere to that standard unless specifically trained. The “gemäßigte Hochlautung” (moderate standard pronunciation) allows for a little more leeway but still does not comprise the full range of pronunciations which would generally be perceived as correct, distinct, and free from local accent. Nonetheless, despite its orientation at the stage and its bias toward North German regional pronunciation, Siebs's work is the best basis for defining a standard German pronunciation. In this article, whenever the “standard” is mentioned, Siebs's Deutsche Aussprache, 19th edition, ISBN 3-928127-66-7, is meant. The examples written phonetically in this article follow this standard with an exception explained in the next section. Apart from the treatment of the <r>, this is one of several possible natural pronunciations.
German vowels are to be differentiated according to following criteria:
7 base qualities written <a> / <ä> or <e> / <i> / <o> / <ö> / <u> / <ü> or <y>, pronounced [a] or [A] / [E] or [e] / [I] or [i] / [O] or [o] / [Ø] or [ø] / [U] or [u] / [Y] or [y].
2 subqualities: open ([a], [E], [I], [O], [U], [Ø], [Y]) and close ([A], [e], [i], [o], [u], [ø], [y]). For the base quality written <a>, the difference is minor and indeed neglected in the current standard but not in older versions of it nor in other dictionaries. We use here both [a] and [A] while the standard uses [A] everywhere.
2 lengths: short and long.
several stress intensities: primary stress, various degrees of secondary stress, no stress. For the purpose of this article, we distinguish only “stressed” (in our phonetic notation denoted by an apostrophe before the syllable with the primary stress, or by a comma before a syllable with a secondary stress) from “unstressed” (denoted with no stress mark before the syllable), but it takes a whole section on stress to define these terms in a way that they fit the purpose.
Stressed short vowels are open. Stressed long vowels are close with the exception of the base quality written <ä> or <e> which occurs both open ([E:] written <ä>) and close ([e:] written <e>). Short <ä> and <e>, however, are both open [E] with no difference between them. We thus get 15 different vowels with length sometimes denoted by gemination or by an <h> after the vowel in the same syllable:
| pronounced | [a] | [A:] | [E] | [E:] | [e:] | [I] | [i:] | [O] | [o:] | [Ø] | [ø:] | [U] | [u:] | [Y] | [y:] |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| written | a | a,aa,ah | ä,e | ä,äh | e,ee,eh | i | i,ie,ieh,ih | o | o,oo,oh | ö | ö,öh | u | u,uh | ü,y | ü,üh,y |
All differences are phonemic: minimal pairs for length and open/close differences are alle–Ahle, Stelle–stähle–stehle, still–Stiel, offen–Ofen, Hölle–Höhle, Busse–Buße, wüsste–Wüste; minimal pairs for unrounded/rounded differences are kennen–können, lesen–lösen, Kiste–Küste, Kiel–kühl.
Unstressed vowels are short. They are open (or close) if they would be open (or close) also when stressed. As an exception, the unstressed <e> in some prefixes and suffixes is realised as a Schwa, e.g. gegebene [g@'ge:b@n@] (more details see below). For syllables ending with a vowel, this exception accounts for much more cases than the rule, so that the combination “unstressed, close, and short” occurs infrequently and mostly in words of foreign origin, e.g. Tomate [to'mA:t@], Regal [re'gA:l], the only frequent Germanic such word being lebendig [le'bEndIç] with its somewhat nonstandard stress pattern. The difference between open and close unstressed vowels is not phonemic, and is often neglected even by many native speakers who pronounce all unstressed vowels short and open.
A German word can have several syllables that are stressed to a varying extent, usually with one syllable carrying the primary stress.
In compound words, the stressed syllable of each component remains stressed to some extent—either becoming the syllable with the primary stress or one of the syllables with a secondary stress of the compound. As the pronunciation of the vowels does only depend on whether they are stressed but not on the intensity of the stress, it is not important for the vowel quality to know which component will get the primary stress. Nonetheless, we give a short overview over the most frequent cases:
Compound verbs composed of a preposistion and a verb can have their primary stress either on the preposition (separable verb) or on the second component (inseparable verb). All verbs with ab-, an-, auf-, aus-, bei-, dar-, ein-, her-, hin-, nach-, vor-, and zu- are separable, many but not all verbs with hinter-, über-, and unter- are inseparable, and with other prepositions, both types of verbs occur.
When the first component qualifies the second, e.g. Bríeftasche which is a special kind of Tasche, the first component gets the primary stress. Most compound nouns are of this pattern.
When the two components were originally two words, e.g. Lebewóhl from Lebe wohl!, or when both components contribute equally to the to the meaning of the compound, e.g. hinwég meaning hin and weg, the second component often gets the primary stress.
In compound nouns of more than two components, the second component often gets the primary stress, especially when the first component qualifies the remainder of the compound, e.g. Oberlándesgericht. It is, however, unpredictable whether this rule applies for a given word.
The remaining portion of this section deals only with non-compound words: what is called a “word” there may either be an isolated word or one component of a compound word.
The normal rule for words of Germanic origin is that they have their stress on the word's root, that is, the portion which remains when all prefixes and suffixes are stripped off. If the word is not entirely of Germanic origin but contains Germanic prefixes and suffixes as discussed in this paragraph, one can at least say that the stress is not on one of these. Very often, the root is monosyllabic even for quite long words, e.g. Eig-en-tüm-lich-keit-en with no less than five suffixes, none of which ever takes the primary stress. Most of the suffixes start with a vowel; for these, the border between root and suffix or between two suffixes is not a border between syllables.
For the purpose of this rule, one may regard some endings as suffixes even when they are part of the word's root. For instance, in the word eigen, eig- has no meaning of its own so that the -en, strictly speaking, belongs to the root. The stress pattern is, however, exactly the same as if -en were a suffix attached to a root eig-, and we make no mistake when we regard it as a suffix, thus saving the labour of detemining whether it belongs to the word's root.
Here are the prefixes and suffixes that have to be considered:
“Light” prefixes form a syllable of their own and are never stressed: be-, ge-, ent-, er-, ver-, zer-.
“Light” suffixes form a new syllable normally beginning with the consonant preceding the suffix; they, too, are never stressed: -e, -el, -em, -en, -end, -er, -es, -est, -et. The <e> often drops out when another suffix beginning with a vowel follows or when it belongs to a case or plural ending, e.g., Händlern = Händ-(e)l-er-(e)n. Of course, it can happen that the word root ends with similar patterns by coincidence. Other “light” suffixes are -ung, -nis and, less frequent, -ig and -ling for forming nouns, -in for turning a generic noun into one referring to a female, the diminutive ending -chen for nouns, and -ig and -lich for forming adjectives. By starting with a consonant, -nis, -ling, -chen, and -lich each are a syllable of their own.
“Heavy” suffixes like -bar, -los , -sam for forming adjectives and -heit, -keit, -lein, -sal, -tum for forming nouns (the last one getting an umlaut when combined with further suffixes: -tümlich, -tümer) do not take the primary stress but they get enough stress that they retain their long vowels. -schaft for nouns and -haft for adjectives have a similar intonation but are short.
When the word root, after stripping off all prefixes and suffixes, is not monosyllabic, the primary stress is not always predictable. The more frequent cases are:
Polysyllabic roots of German origin are very often stressed on the penultimate syllable. This is the reason why we could remove the light suffix of, say, eigen, even though it belongs to the root, thus leaving a monosyllabic kernel of the root which is indeed the stressed syllable. Other cases are:
If a light suffix has been stripped off which belonged to the root, i.e. which appears in all words with that root, then the syllable before this light suffix is mostly the stressed one, and the preceding syllable is unstressed: Wachólder, Kartóffel, Hornísse.
If, however, the entire root contains no light suffix, the primary stress is more typically on the first syllable with the second one getting more or less of secondary stress: Árbeit, Mónat (here -at is not a Latin ending), Hérzog.
Words with Latin and French endings (-abel, -ade, -age, -al, -and, -ant, -anz, -ar, -är, -at, -ei, -ell, -end, -ent, -enz, -esk, -ett, -eur, -ibel, -id, -ie, -ier, -ik, -ikt, -il, -ion, -ismus, -ist, -it, -itis, -iv, -or, -os, -ös, -tät, -ur) are stressed on this ending or on the first syllable thereof, leaving the preceding syllables unstressed. As an example, Denunziantentum is first freed from the Germanic endings yielding Denunziant(-en-tum), then stressed on the Latin ending: Denunziántentum[denUn'tsjant@n,tu:m]. For some of these endings, there are special observations:
The ending -ik is not always stressed, e.g. Genétik, Lógik, and is never stressed with the ending -er, e.g. Mathematík (in Austria Mathemátik) but Mathemátiker; when unstressed, the <i> is an open [I]. -iv has sometimes only a secondary stress, especially in grammatical vocabulary (Nóminativ), and so has -or in medical vocabulary (Túmor) and also elsewhere; note the different stress for the two meanings of tenor: Tenór (highest male voice) and Ténor (general drift of a document).
The ending -ion is only one syllable and is stressed on the <o>: [-jo:n].
The ending -ei is partly Germanized from French -ie: it is stressed like the French original but does not take away a secondary stress from the preceding syllables, e.g. Maleréi with enough stress remaining on the <a> that it can be long.
The ending -ie exists in a stressed [-i:] and an unstressed [-i@] variant; in the latter case the stress is on the preceding syllable: Manie [mA'ni:], Familie [fA'mi:li@], Zeremonie either as [tseremo'ni:] or [tsere'mo:ni@]. There is no way to tell the pronuncation of a given word ending with -ie.
The ending -ier on nouns is mostly pronounced the German way as [-i:r] (Barbier) and sometimes the French way as [-je:] (Bankier); both variants take the stress. Again, there is no way to tell which pronunciation applies for a given word. The verb ending -ieren is always pronounced [-i:r@n] with the stress on the [i:].
Words imported from other languages have often the stress pattern of the language where they originate, or the stress appears to be irregular. For instance, compare Páratyphus, Parámeter, Paraphráse. Some even change the stressed syllable: Álgebra (in Austria Algébra) but algebráisch, Algébren.
For the vowel length in a prefix or first component of a compound word not carrying the primary stress, it makes a difference whether it is regarded as an unstressed prefix or as a first component with secondary stress. While this distinction is clear for light prefixes on one hand and for autonomous first components on the other hand, opinions may be divided for prepositions. In practice, the long and close vowels of über-, vor- and zu- are pronounced close and short when unstressed; the standard has long [?y:b@r-], short [tsu-], and varying [fo(:)r-]. A special case is her- which is a long and close component of a compound [he:r-] when stressed but a short and open light prefix [hEr-] when unstressed.
The simplest cause for two vowels to appear adjacent in the written form of a word is a syllable boundery between them. There are, however, several situations where the two adjacent vowels belong to the same syllable:
The second vowel lengthens the first one. In standard German, this is only the case for <aa>, <ee>, <oo> and for <ie> (Biene ['bi:n@]). In North German, thus Low German, placenames, this happens also with other vowel pairs (Grevenbroich [,gre:v@n'bro:x], Coesfeld ['ko:sfElt], Kevelaer ['ke:v@,lA:r]).
The two vowels form a diphthong: <ai> or <ei> pronounced [ae], <au> pronounced [ao], <äu> or <eu> pronounced [Oø]. The second vowel of each diphthong is pronounced shorter and less stressed; they are defined as close in the standard; however, open pronunciation, that is, [aI], [aU], [OI], is also quite common.
The first of the vowels is a <u> following a <q>: then it is a in fact a consonant (<qu> is pronounced [kv]), so that it is not part of a vowel cluster.
The two vowels serve as a surrogate for an umlaut, that is, <ae> for <ä>, <oe> for <ö>, or <ue> for <ü>. Unless the character set of the medium misses the umlauts, this is regarded wrong spelling. Such combinations do, however, appear in proper names (Goethe ['gø:t@], Uelzen ['?Ylts@n]).
In Middle High German, the two vowels formed a diphthong which has left its traces in Swiss or Bavarian, e.g. MHG/Sw. <ou>, <uo>, <ie>, <üe>, Sw. <ue>, Bav. <oa>, <ia>, <ua>. Such old diphthongs, also with their stress on the first vowel, appear only in proper names (Lienz ['liEnts], Ruedi ['rUEdi]) and in a few loanwords from Swiss German (Müesli ['mYEslI] = oatmeal porridge).
Particularly in the context of proper names, it is sometimes difficult to tell which case applies. For instance, compare the place names Itzehoe [,?Its@'ho:], Laboe [lA'bø:], and Buchloe ['bu:xlo@] with three differently pronounced -oe at the end. Apart from proper names, things are usually much clearer.
In German, word roots never begin with a vowel. When they are written with a vowel at the beginning, they are pronounced with an unwritten consonant, the glottal stop [?], which is used both at the beginning of a word (Arbeit ['?A:rbaet]) and within a word at the beginning of the root (bearbeiten [b@'?A:rbaet@n]). There is no glottal stop between two vowels in the same morpheme, e.g. Theater [te'A:tEr], nor between root and ending (compare Malerei [,mA:l@'rae] and Osterei ['?o:stEr,?ae]). Some compositions are so common that they are now perceived as a single root so that the glottal stop between the morphemes is lost: vollends ['fOlEnts], reagieren [reA'gi:r@n], but reanimieren [re?Ani'mi:r@n] (the standard suggests no glottal stop for the first of these and an optional one for the other two).
In particular, there is no glottal stop in words like hinab or darauf: compositions of hin-, her-, vor- with -ab, -an, -auf, -ein, -aus, -unter, -über are stressed on the second component with no glottal stop between. When two vowels come together in compositions of da-, wo- with -an, -auf, -in, -aus, -unter, -über, an extra <r> is inserted so that the pronunciation without the glottal stop is facilitated. The hyphenation may today follow either the composition point (hin-ein, vor-über, dar-auf) or the spoken syllables (hi-nein, vo-rüber, da-rauf); prior to the spelling reform in the 1990ies, it had to be done the former way. As only exception, vorab is pronounced with a glottal stop: [fo:r'?ap]. (Of the words constructed as indicated above, *vorein and *vorunter do not exist.)
After all these necessary preliminaries, we get back to the question of how to determine the quality and length of a vowel from the written form of the word. We remember from the section on the vowel system that there are mainly three kinds of vowels in German:
long vowels, which are typically close; more precisely vowels that are long if stressed and short if unstressed, and close unless written <ä>.
short vowels, which are always open; more precisely vowels that are short and open irrespective of stress.
Schwa, that is, the vowel written <e> in some unstressed syllables where it is pronounced [@].
(Note that close unstressed vowels are contained in the first group although they are in fact short.)
Below, rules are given for determining which of these three cases applies when, which is often, albeit not always, possible from the written form of the word, provided the stressed syllable is known. The scopes of the rules are not always mutually exclusive; then the earlier rules take precedence.
The vowel in a light prefix or suffix (cf. section on stress) is short and open. If it is an <e>, it is pronounced
as a short open [E] in a prefix when the prefix ends with a consonant: her- (only when unstressed), ent-, er-, ver-, zer-,
as a short open [E] in a suffix when an <r> follows, and
as a Schwa [@] in all other cases.
The standard makes much more distinctions about which alternate pronunciations are admissible in which contexts, but the above rules cover all cases in a standard-conformant way.
All vowels are long when there is an <h> following in the same syllable. The vowels <a>, <e>, and <o> are long when they are geminated. The vowel <i> is long when it is written <ie> or <ieh>. Vowels can be long without being marked as long by these means; typically, only stressed vowels are in this way marked as long.
Note that most intervocalic <h> within morphemes are not pronounced but serve only to indicate the length of the preceding vowel, e.g. nahe [nA:@], Mühe [my:@]; nonetheless the hyphenation rules demand that the <h> is written on the new line with the following syllable. Exceptions are Ahorn and interjections like aha: there the <h> is spoken and belongs to the second syllable.
All vowels are short when the following consonant is geminated; when <k> and <z> are geminated they become <ck> and <tz>. Mainly stressed vowels are in this way marked as short, plus vowels other than <e> in light suffixes when they lose their final position: -in–>-innen, -nis–>-nisse, although not -ig–>*-igge. With very few exceptions, geminated consonants appear only at the word end or between vowels, or when additional consonants have been inserted by an inflexion, e.g. es hallte from the verb hallen.
Consonants written as digraphs or trigraphs (<ng>, <ch>, <sch>) cannot be geminated, nor can <x>. In addition, <st> and <tsch> also behave like single consonants that cannot be geminated. The vowel before <ng> and <x> is always short, for <ch>, <sch>, <st>, and <tsch> see rule 7 below.
<s> can in principle be geminated to become <ss> but due to changing usage of <ß> and <ss> in different countries at different times one has to be cautious about inferring the length of the preceding vowel:
In German and Austrian texts adhering to the rules of the spelling reform in the 1990ies, <ss> marks the preceding vowel as short and <ß> marks the preceding vowel as long.
In German and Austrian texts written prior to that reform or ignoring its rulings, the same holds with the exception that the vowel preceding an <ß> can be either short or long when no vowel follows.
In Swiss texts, <ß> is not used and the vowel preceding an <ss> can be either short or long.
In a polysyllabic word, a vowel is long if it is followed (before the next vowel or the word end) by at most one consonant that could be geminated but is not. In particular, the stressed French and Latin endings (cf. section on stress) contain long vowels unless they end in two consonants. The endings -ik as in Musik and -it as in Bandit are pronounced short as [-Ik] and [-It] in wide parts of Germany; however, the standard insists on the Northern variant with long vowel [-i:k] and [-i:t] (again with an exception: in chemistry and mineralogy Sulfid [zUl'fi:t] and Sulfit [zUl'fIt] must be discernible).
The vowel in uninflected monosyllabic words such as articles, pronouns, and prepositions is
long when there is a single <r> after the vowel at the word end, in dem, wem, den, wen, and, restricted to North German usage, also in schon,
long when the vowel is at the end of the word, and
short in all other cases.
As many of these words are unstressed, thus short, in the context of a sentence, “long” means basically “close”. As already mentioned, the vowel of her [he:r] changes to open when it appears unstressed in a composition as her- [hEr-].
The vowel in inflected monosyllabic words such as adjectives and nouns is
long when inflected forms have also a long vowel by rule 4 (Tal–>Täler, Weg–>Wege, schwül–>schwüler) or when there is a single <r> after the vowel at the word end, and
short in the remaining cases.
Nearly all examples with short vowels are of English origin (non-English are Bus, Chef, Kap, and Tic). Nouns build their plural mostly by appending <s>, and other derivations are done by geminating the final consonant, e.g. poppig from Pop. In order to reduce these cases, the spelling reform in the 1990ies modified the former Mop, Step, Stop, and Tip to become Mopp, Stepp, Stopp, and Tipp, but they missed out on Bit, Bob, Bus, Chat, Chef, Chip, Clip, Club, Dip, fit, Flip, Flop, hip, Hit, Jet, Job, Kap, Kit, Lop, Mob, Net, Pep, Pop, Set, Shop, Slip, Snob, Spot, Sprit, Strip, Tic, Top, Trip, Twen, and Web.
The length of a vowel that is followed by <ch>, <sch>, <st>, or <tsch> at the word end or between vowels is not always predictable. The same holds for the vowel followed by <ß> or <ss> in that position in those cases where rule 3 yields no result. The following guidelines are helpful for guessing the length of the vowel with quite some reliability:
<e> and <i> before any of these consonant patterns are short.
All vowels before <sch> are short, with very few exceptions where <u> und <ü> are long before <sch>.
<u> und <ü> are mostly long before <ch>, with the exception of nouns directly derived from verbs not already containing the <u>, e.g. short Bruch, Geruch, but long Suche.
<a> and <ä> are mostly short before <st>.
In the remaining cases, the length of the vowel is hardly predictable, perhaps with a slightly better chance of being short.
Before <r> and a following dental sound ([d], [t], [s], [S]), <a>, <ä>, <e>, and <ö> can be short or long. Northern pronunciation often prefers long vowels where Southern prefers short ones, e.g. in erst and Behörde; in other cases, one of short or long is used nearly everywhere, e.g. Herz [hErts] and Erz [?e:rts]. The standard has again a preference for Northern pronunciation, although it recognises some short variants as regionally valid Austrian or Swiss pronunciations. The actual distribution of long and short pronunciation for these words is in fact much more irregularly scattered across the German-speaking countries, the above North-South distinction only being a general trend.
A vowel is long if the vowel in the word stem is long by the preceding rules, even when it is followed by two or more consonants, e.g. malst [mA:lst] from malen ['mA:l@n]. In some words, the stem is not easy to recognise: nebst (from neben), stets (from stet), beredt (from reden).
In nearly all remaining cases where a vowel is followed by two or more consonants, it is short. There are, however, a handful of exceptions to this rule: Obst, Jagd, Magd, Krebs, and Papst had two syllables until not long ago, Mond acquired its final -d only recently, and Keks and Koks are recent loans from English cake and coke.