Twenty-five letters · Four groups · One stem
Each letter named for a tree. Each stroke placed with purpose. Read from root to crown.
How it works
Every Ogham letter is built from notches and strokes laid across a central line called the flesc. On standing stones this line was the edge of the stone itself — the corner became the stem, and the letters were carved either side of it.
The twenty-five letters are divided into four groups called aicmí (singular: aicme), each named after its first letter. A fifth group — the forfeda — was added later to represent sounds that came into Irish through borrowing from Latin and Norse.
Direction matters. Classical Ogham on stone reads from the bottom of the stem upward — you place your finger at the base of the stone and follow the strokes toward the sky. In manuscripts and in modern use, Ogham is written horizontally, left to right, which is the convention used throughout this site.
The letter names are drawn from the natural world — trees, plants, and shrubs familiar to early Irish people — giving the alphabet a particular character: rooted, seasonal, alive.
Read bottom to top. Found on standing stones across Ireland and Britain. The stone's edge forms the stem.
Read left to right. Used in manuscripts from the 7th century onward and in all modern contexts.
The letters
Hover any letter to see its full name. The stem colour indicates its group.
Missing letters
Classical Ogham was designed for Old Irish — a language that simply did not use certain sounds that are common in modern English. The letters J, K, P, V, W, X, Y, and Z either did not exist in Irish phonology, or were so rare that no dedicated Ogham character was ever created for them.
This is not a flaw — it reflects the fact that Ogham was built for one language and later borrowed by others. When we transliterate modern English into Ogham we are doing something historically unusual: using an ancient Irish script to represent sounds it was never designed to carry.
The substitutions below follow the most widely accepted modern scholarly convention — matching each missing letter to its closest phonetic equivalent in the classical alphabet. Where a sound has no single match, a compound of two letters is used. These substitutions are shown clearly whenever they are applied, so nothing is hidden.
Each missing English letter mapped to its Ogham equivalent, with the reason why.