🌳 Celtic Tree Sign Calculator — Your Ogham Tree by Birth Date
Enter your birth date and Umbriel finds your Celtic tree sign, free. Celtic tree astrology assigns each of thirteen lunar months a tree drawn from the ogham alphabet — Birch, Rowan, Ash, Alder, Willow and on through the year.
- What you'll needBirth date
- What you getYour tree from the thirteen-month Beth-Luis-Nion calendar, with its ogham letter and associations
- CostFree — no account required
Runs in your browser. Nothing to install, nothing to set up.
What Celtic tree astrology actually is
The system uses the Beth-Luis-Nion sequence, named for its first three letters, and divides the year into thirteen roughly 28-day months, each governed by a tree. Every tree carries an ogham letter, a set of associations, and a place in the turning year — Birch at the year's rebirth, Elder at its close.
Honesty matters here, and it's a place a lot of sites are vague: this arrangement is modern. It draws on genuinely ancient material — the ogham alphabet is real, and Old Irish sources do associate letters with trees — but the specific 'your birthday means you're a Willow' calendar comes largely from twentieth-century writers, Robert Graves in The White Goddess foremost among them.
That doesn't make it worthless. Trees are a good vocabulary for character, and a system keyed to the actual turning of the year has a rhythm most zodiacs lack. Just take it as poetry with roots rather than a druidic inheritance.
What's in your result
- Your treeOne of thirteen, set by where your birthday falls in the lunar year.
- Its ogham letterThe character from the ogham alphabet the tree is named for.
- The tree's associationsQualities traditionally attached to that tree in the folklore the system draws on.
- Where it sits in the yearWhether your tree governs the year's opening, its height, or its close.
Common questions
Is Celtic tree astrology authentically ancient?
Partly. The ogham alphabet and tree-letter associations are genuinely old, but the birthday calendar built on them is largely twentieth-century, popularised by Robert Graves. It's better described as modern work built on ancient material.
Do I need my birth time?
No — only the date. The tree months are fixed date ranges, so the date alone settles it.
What if my birthday falls on a boundary?
The month boundaries fall on fixed dates, so a birthday on one is assigned to the month it starts. Umbriel's calculation covers every day of the year, with no gaps or overlaps.
Is it free?
Yes, no account needed.
Related free tools
Umbriel offers every system here as a set of prompts to think with, never as a statement of fact about who you are. Take what's useful, leave the rest.