Greek Tonos & Dialytika - Alt Codes & Unicode

Modern Greek uses a single accent, the tonos, which marks the stressed syllable of any word of two or more syllables. This is the monotonic system, adopted officially in 1982, and it replaced the far more elaborate polytonic system of acute, grave, circumflex and two breathing marks that Greek had carried since antiquity. If you are writing modern Greek, one accent is all you need, and it goes on the stressed vowel: καλημέρα, Ελλάδα, άνθρωπος.

There is one trap in Unicode that catches almost everyone working with Greek text, and it is worth understanding before you debug anything else. The correct modern Greek accented vowels are the tonos characters at U+03AC and following — ά, έ, ή, ί, ό, ύ, ώ. There is a second, nearly identical set called the oxia, at U+1F71 and following, which belongs to the polytonic block. They render identically in most fonts and are completely different characters. Text mixing them will fail to match in search, fail to deduplicate, and sort inconsistently. Unicode normalisation form NFC maps oxia to tonos, so running Greek text through NFC normalisation resolves this, and it is the standard fix.

The dialytika, the two dots on ϊ and ϋ, does the same job as a diaeresis in French or Dutch: it splits a vowel pair that would otherwise be read as one sound. Παϊδάκια keeps the alpha and iota separate. When a vowel needs both the dialytika and the accent, Greek has dedicated precomposed characters, ΐ and ΰ, which are in the table above. Do not try to build them by stacking two marks — use the single character, or matching will break the same way it does with oxia.

Capitals follow a rule that surprises people: a capital letter at the start of a word keeps its accent when the word is in mixed case, so Άννα and Έλλη take the tonos, but a word set entirely in capitals drops accents altogether, so ΑΝΝΑ has none. The dialytika, however, is retained even in all-caps, because it carries information about pronunciation rather than stress. Headlines and signage in Greece follow this consistently.

On Windows, Alt codes for Greek are unreliable because they depend on the active codepage; the Greek keyboard layout is the practical choice, and it places the tonos on the semicolon key as a dead key, so pressing it then a vowel produces the accented form. Note that this same key produces the Greek question mark, which looks like a semicolon. On macOS, select the Greek input source and use Option+semicolon or the dead-key equivalent. On Linux, choose the Greek layout and the accent key behaves the same way. On mobile Greek keyboards, long-press the vowel to reach the accented form.