The traditional Finnish alphabet, as taught at Finnish schools, is the same as the basic Latin alphabet with the letters Å, Ä, and Ö added at the end: A B C D E F G H I J K L M N O P Q R S T U V (W) X Y Z Å Ä Ö. It is the same as the traditional Swedish alphabet, and the letter Å is included only due its use in Swedish.
The role of the letter W is ambiguous. Historically, it is a variant of the letter V and appears in some Finnish names, such as the surname Wirtanen, a rare variant of the very common name Virtanen. Traditionally, W has been treated as equivalent to V in sorting. On the other hand, W appears in foreign words such as show and watti (watt), and it is nowadays often treated as a separate letter in sorting, as in English.
The names of the traditional letters are aa, bee, see, dee, ee, äf, gee, hoo, ii, jii, koo, äl, äm, än, oo, pee, kuu, är, äs, tee, uu, vee, (kaksoisvee,) yy, tseta, ruotsalainen oo, ää, öö. When reading an abbreviation by letters, w is usually read as vee, e.g. WWW as vee vee vee, but kaksoisvee can be used for clarity.
Instead of äf, äl, äm, än, är, äs, the longer forms äffä, ällä, ämmä, ännä, ärrä, ässä (often shortened to äff, äll etc. before a vowel) can be used, and these forms must be used as the basis in inflection; e.g., the genitive of äf is äffän. These names, except är(rä), also appear with e instead of ä, e.g. ef or effä. The use of the forms with e is often regarded as Swedish influence, and it has lost popularity, except in contexts where it is phonetically better due to vowel harmony, e.g. in reading USA as uu ess aa.
The common spelling alphabet (names used when saying a word letter by letter) is Aarne, Bertta, Celsius [selsius], Daavid, Eemeli, faarao, Gideon, Heikki, Iivari, Jussi, Kalle, Lauri, Matti, Niilo, Otto, Paavo, kuu, Risto, Sakari, Tyyne, Urho, Vihtori, wiski [viski], äksä, Yrjö, übel [yybel], tseta, Åke [ooke], äiti, öljy.
According to the official orthography, as amended in the early 20th century, Š and Ž belong to the alphabet, too, but they are treated as S and Z in sorting. Their Finnish names are hattuässä and hattutseta.
Although the basic alphabetic order in Finnish is well-established, except for the changed status of W, there are many difficulties in putting expressions in alphabetic order when foreign letters and non-alphabetic characters are included.
There are even several conflicting national standards on sorting: SFS 4600, which is little known and little used and impossible to apply automatically; SFS 5050 for bibliographic sorting; and SFS-EN 13710, which is based on a pan-European standard, with some adaptations to Finnish usage.
According to SFS-EN 13170, the basic order of letters A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Þ Å Ä Ö. This means that W is a separate letter, and the Icelandic letter thorn Þ (þ) is placed after Z. Other added letters, like the Icelanding eth Ð (ð), are treated as variants of basic letters like D; the difference is taken into account only in words that are otherwise identical.
Most diacritic marks are ignored, except of course for Å, Ä, and Ö. For example, É is sorted like E, just so that in otherwise identical words like Linden and Lindén, the one with the diacritic mark comes later. However, for historical reasons, SFS-EN 13710 makes the following exceptions from pan-European rules, reflecting relatively well-established Finnish practices:
Case of letters is ignored in sorting, except when two strings differ only in case of some letter(s). In that situation, lower case is sorted before uppercase. This means that in a glossary, a common name like meri (sea) should precede an identical proper name, like Meri as a surname.
SFS-EN 13170 sorts data as strings, with no regard to meaning. This makes it possible to apply it automatically, but it also makes the results unintuitive in a manner that may require tuning. The overall order of characters is:
This means e.g. that the name Suomen ympäristökeskus appears before Suomenlinna, since the space is counted as a character and precedes all letters. Similarly, golf-osake is sorted before golfkenttä. Thus, the placement of an expression may depend on its spelling as an open compound, a closed compound, or a hyphenated compound. Some older practices still in use, and defined in SFS 4600, try to avoid such problems by ignoring most other characters than letters and in one mode of sorting, called sanoittainen lajittelu (sorting by words), even spaces.
When sorting personal names, it is common to ignore prepositions at the start of surnames, e.g. sorting af Julin as Julin and von Schulz as Schulz. However, this is not consistent, and SFS 4600 defines how different prepositions are handled differently.
Only the following letters appear in Finnish words, when foreign words (loanwords that preserve the original spelling) are not considered: A B D E F G H I J K L M N O P R S Š T U V Y Z Ž Ä Ö. Of these, letters B, F, Š, Z, and Ž appear in relatively new loanwords only. For more details on the use of letters in Finnish texts, see section A closer look at the use of letters in Finnish texts.
The basic phonetic values are described in section Pronunciation of letters.
Historical note: In a book on Finnish phonetics and orthography, Suomen kielen äänne- ja oikeinkirjoitusoppi (published in 1949), Aarni Penttilä wrote about the alphabetic order as consisting of “a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, (š), t, u, v, x, y (ü), z, (ž), å, ä, ö (ø), (õ)”. According to him, this list constitutes suomalais-ruotsalainen aakkosto (Finnish-Swedish alphabet) when the letters in parentheses are omitted. He described the letter w essentially as a stylistic variant (allograph) of v and as a holdover from Fraktur fonts.
In informal writing, the letter x is sometimes used (irregularly) instead of ks, e.g. writing colloquial yks (standard Finnish yksi, “one”) as yx. Other casual playful writing styles include using z for ts, q for kuu (e.g. qkausi for kuukausi, “month”) and c for see.