🌳 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.
OTHER SYSTEMNot astrology: its own system, presented as such.
- 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
What Celtic tree astrology 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, not a druidic inheritance.
How Umbriel computes it
This tool looks up your Celtic tree sign from your birth month and day using a fixed table of thirteen trees. The table in Umbriel runs Birch from 24 December to 20 January, Rowan 21 January to 17 February, Ash 18 February to 17 March, Alder 18 March to 14 April, Willow 15 April to 12 May, Hawthorn 13 May to 9 June, Oak 10 June to 7 July, Holly 8 July to 4 August, Hazel 5 August to 1 September, Vine 2 to 29 September, Ivy 30 September to 27 October, Reed 28 October to 24 November and Elder 25 November to 23 December. The code converts your month and day to a single number (month x 100 + day) and returns the tree whose range contains it, wrapping across the new year for Birch. Only your birth month and day are used: the year, time and place make no difference, the ranges are the same every year, and there is no astronomy in it. The page also reports roughly how many days you were born from the edge of your tree, and it does not blend neighbouring trees. This is a symbolic calendar of dates, not a measurement, so it has no accuracy figure, and other sources draw the boundaries differently.
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.
Do I need an account or an email address?
No. There is no sign-up, no email capture and no free trial. Enter your details and the result is drawn in your own browser.
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.