Consonant gradation in Finnish – the true story

There is a lot of information available about consonant gradation (Finnish: astevaihtelu) in the Finnish language, but it is mostly incomplete and even partly incorrect. One reason for this is that most presentations do not distinguish the assumed history of the phenomenon from its nature in modern Finnish. Moreover, orthographic conventions can be misleading; contrary to widespread claims, Finnish orthography is not purely phonemic, as described in Finnish my treatise Onko suomen kirjoitusjärjestelmä ihanteellinen?

This document focuses on the consonant gradation in modern Finnish, mostly in standard Finnish. Its history is interesting, but it is easy to get misled if you analyze the present through the historic background.

The basic definition

Consonant gradation is a specific kind of allomorphic variation between alternatives called strong grade and weak grade involving a stop (a k, p, or t sound, or rarely a g or b) at least in the strong grade. The weak grade mostly appears at the start of a closed syllable (i.e., a syllable ending with a consonant). Gradation only takes place inside a word after a voiced sound.

For example, the Finnish word kuppi (cup) ends with an open syllable, and the double consonant pp represents the strong grade. When the plural suffix t is appended, the double consonant pp is replaced by the simple consonant p, producing kupit.

Note that in Finnish, the difference between pp and p is not just orthographic. A double consonant is pronounced clearly longer than a single consonant. It is called a double consonant for reasons of convention. Conventionally, a syllable boundary is said to exist between the components of a double consonant, and the hyphenation rules reflect this: the allowed hyphenation is kup-pi.

There are exceptions to the rule that the weak grade appears at the start of a closed syllable. For example, the word form kuppiin ends with a closed syllable but has the strong grade. There are even apparent contradictions like tiede : tieteen, where the weak grade seems to appear before an open syllable (though in reality, tiede normally ends with an assimilated consonant in pronunciation) and the weak grade appears before a closed syllable. In this document, we will not discuss the detailed conditions for strong vs. weak grade. Instead, we consider the various types of gradation.

Quantitative and qualitative gradation

Many presentations, including Iso suomen kielioppi, an extensive but rather unsystematic descriptive grammar of Finnish, claim or imply that gradation is alteration of stops. This is not correct. Consonant gradation consists of two phenomena:

In qualitative gradation, the weak grade has a stop only in the t : d alteration. Besides, this alteration only occurs in standard Finnish, as a result of an artificial solution with a curious history. Practically no dialect has d (or any other stop) as the weak grade consonant. (Standard Finnish practice in this issue, though originally artificial and literary, has however become widespread in modern spoken language.)

Notes on quantitative gradation

Quantitative gradation is relatively simple. The conditions for the use of strong vs. weak grade aside, the deviations from the simple principle described above can be summarized as follows:

Forms of qualitative gradation

In the following summary table, the following notations are used in the second column that indicates the weak grade:

Forms of qualitative gradation
Strong Weak Condition Example Note
t d Usually katu : kadun In standard Finnish
: After l, n, r pelto : pellon  
p v Usually lupa : luvan Finnish “v” is an approximant
: After m sampo : sammon  
k Usually haku : haun  
v Between u’s or y’s puku : puvun  
j Between h/l/r and e/i kulkea : kuljen – (kulen) in many dialects
g After n lanka : langan ng pronounced as [ŋŋ]

Special phenomena in qualitative gradation


A short stop does not have gradation in words of the following classes:

Direct vs. inverse gradation

Some presentations, including Iso suomen kielioppi, distinguish between direct (suora) and inverted (käänteinen) astevaihtelu. Gradation is called direct, if the base form of the word has strong grade, otherwise it is called inverted. For example, hyppiä : hypin has direct gradation, hypätä : hyppään has inverted gradation.

These concepts are mostly just confusing. They depend on what form is called the base form, which is more or less arbitrary and a matter of grammar rather than language. For nouns, it is natural to treat the nominative singular as the base form, since it has no case suffix in Finnish. Yet it can be exceptional rather than typical as regards to allomorphic variation inside a paradigm. For verbs, the infinitive commonly regarded as the base form is not really basic: it always has a suffix, and it does not even exist for some words. Some old dictionaries use the 1st person singular of the infinitive as the base form; from a logical point of view, 3rd person singular would be more appropriate, since it exists for all verbs and it is usually the most common form.

Anyway, the base form, however we define it, is in no particular role in gradation. It has strong or weak grade according to same principles as other forms. The distinction between direct and inverse gradation is probably useful only in the practical use of dictionaries, and even this is debatable.

Finnish dictionaries typically indicate the presence of gradation with an asterisk the word e.g. as follows:


Here the superscript number (1) refers to a inflection class, as numbered in the dictionary, and the asterisk (*) indicates that there is consonant gradation in the word. So how can you know whether the base form has weak or strong grade, i.e. whether the k varies with kk or with absence of consonant? You might think that you need to know whether the gradation is direct or inverted. But dictionaries don’t tell that to you! For example, Nykysuomen sanakirja does not indicate the specific type of gradation at all, and Suomen kielen perussanakirja indicates it simply by a letter that identifies the type.

In practice, you can usually know the gradation type from the word itself. The word form aikoa has the k at the start of an open syllable, so it is in the strong grade; consequently, the k is lost in writing in the weak grade, e.g. aion (though the pronunciation may have a j sound, as mentioned above).

The only major problem is with words ending with e. However, for them, the inflection class information resolves the issue. You just need to know that for words with inflection like hame : hameen (as opposite to the less common type nalle : nallen), the base form is treated as ending with a consonant, so it has the weak grade; hence e.g. tiede : tieteen.