Ahnentafel Explained

One of the fundamentals of genealogy is the various numbering systems used to make quick and easily-read lists of ancestors and descendants. Perhaps the most common method of listing ancestors is to create an ahnentafel. Yet I suspect that word confuses many newcomers. Here is a (hopefully) simple explanation.

An ahnentafel is a list of one's ancestors with each one numbered in a sequential manner that makes it easy to calculate relationships. The ahnentafel method is the most common method of numbering ancestors

Ahnentafel is a German word that translates as “ancestor table” or, literally, a list of one’s ancestors. The same numbering system is sometimes called the Sosa-Stradonitz System, named after the Spanish genealogist Hieronymus/Jerome de Sosa, who first used it in 1676, and after the German genealogist Stephan Kekulé von Stradonitz [1863-1933], who popularized it in his 1896 Ahnentafel Atlas.

In an Ahnentafel numbering system, the base person is assigned the number one. The father of each person is assigned a number equal to double the child’s number. The mother of each person is assigned a number equal to double the child’s number plus one. As a result, the number of any child is one-half that of their parent, ignoring any remainder. For the first four generations, the numbers assigned a given person and their ancestors reflect the following relationships:

1.   person
2.   father
3.   mother
4.   paternal grandfather
5.   paternal grandmother
6.   maternal grandfather
7.   maternal grandmother
8.   great-grandfather
9.   great-grandmother
10.   great-grandfather
11.   great-grandmother
12.   great-grandfather
13.   great-grandmother
14.   great-grandfather
15.   great-grandmother

Translating this to a real person, here is an excerpt from the Ahnentafel of one well-known American, complete with Ahnentafel numbers:

1. George Walker Bush, b. New Haven, Conn., 6 July 1946, m. 5 Nov. 1977, Laura Lane Welch
2. George Herbert Walker Bush, b. Milton, Mass., 12 June 1924, m. Rye, N.Y., 6 Jan. 1945
3. Barbara Pierce
4. Prescott Sheldon Bush, b. Columbus, Ohio, 15 May 1895, m. Kennebunkport, Maine, 6 Aug. 1921, d. New York, N.Y., 8 Oct. 1972
5. Dorothy Walker, b. near Walker's Point, York Co., Me., 1 July 1901, d. Greenwich, Conn., 19 Nov. 1992
6. Marvin Pierce, b. Sharpsville, Pa., 17 June 1893, m. Aug. 1918, d. Rye, N.Y., 17 July 1969
7. Pauline Robinson, b. Ohio, April 1896, d. Rye, N.Y., 23 Sept. 1949
8. Samuel Prescott Bush, b. Brick Church, N.J., 4 Oct. 1863, m. Columbus, Ohio, 20 June 1894, d. Columbus, Ohio, 8 Feb. 1948
9. Flora Sheldon, b. Franklin Co., Ohio, 17 Mar. 1872, d. "Watch Hill", R.I., 4 Sept. 1920
10. George Herbert Walker, b. St. Louis, Mo., 11 June 1875, m. St. Louis, Mo., 17 Jan. 1899, d. New York, N.Y., 24 June 1953
11. Lucretia [Loulie] Wear, b. St. Louis, Mo., 17 Sept. 1874, d. Biddeford, Me., 28 Aug. 1961
12. Scott Pierce, b. Sparkville, Pa., 18 Jan. [or June?] 1866, m. 26 Nov. 1891
13. Mabel Marvin, b. Cincinnati, Ohio, 4 June 1869
14. James Edgar Robinson, b. near Marysville, Oh., 15 Aug. 1868, m. Marion Co., Ohio, 31 March 1895, d. 1931
15. Lula Dell Flickinger, b. Byhalia, Ohio, March 1875

The primary disadvantage of Ahnentafel numbers is that the size of each number when going back many generations becomes quite large. Someone with a documented line of descent from Charlemagne may be using Ahnentafel numbers in the billions.

Ahnentafel numbers are the only commonly-used numbers for ancestor lists. However, several systems exist for numbering descendants in a list.

Comments

[Pat]

Fantastic........... I have been meaning to learn about this for ages and I am about to reach the point in my data where I really NEEDED to know! I am very grateful for your work and your thoughtfulness.

Pat

[Jennie Jimenez]

Please, Im still lost with this explanation, is there any video on this subject, step by step.
Thank You in advance.

[Albert Edward Belanger]

How about this ?

You are number: 1 (Whether you are male or female)

Male side -

Your father is double your number: 2
His father (you grandfather) is double that: 4
His father (your great grandfather) is double that: 8
Each father of the next generations is double that of the preceeding one.

On the female side -

Your mother is your father's number(2) plus 1: 3
Your grandmother is your grandfather(4)plus 1: 5
Your gr-grandmother is her husband (8) plus 1: 9
Each female, then, is her husband's number plus 1

So when you see a chart, all even numbers are male and uneven numbers are female. Except, however, you are always number 1 whether you are male or female.

You can navigate forward in time: slide down to the next generation by doubling the number. This will give you the father (his wife will be the next name...husband plus 1)

-or-

You can navigate backwards in time from a particular name in the chart by dividing the number by 2 for each previous generation ... That will show the father, and his wife will be the following name on the list.

It helps if you have done your genealogy for four or five or more generations. Just list your names by generation (husband followed by wife)and assign the numbers as above.

Hope this helps.

[Kristy]

One confusion I've had brought up when explaining this is:
What happens when I can go back six generations on dad's side but only three on mother's?

You will have lots of "empty" numbers. That is OK. That is the way of it.
Then, when you get the fourth generation of your mother, you will have places to put those names.

It also gives you a "visual" of where you will need to do more work.

So you -could- take a piece of paper and number it (as in readying for your spelling test) and, eventually, hopefully, you will someday have every number filled with an ancestors names. Beyond a certain number of ancestors tho, you might have pages and pages of emptiness. That's another gift of the computer age. You can put in only the numbers you need now, and insert others as you find them, without having to retype everything. You'll always have a neat, up-to-date-with-research copy to show to others, and to study when you need to move backward.

[Linda Enz]

Dick this info was very useful. I think I will use it to help in numbering my photos. You mentioned some other numbering systems sometime in the future would you be so kind as to share those with us also? What might work or make sense to one person may not work for another. I like options.
Thanx

[Dae Powell]

I like it because it directly applies to pedigree charts. I also like the Register format from the New England group. Both communicate well to most people and that's the purpose, isn't it?

Happy Dae.
http://www.ShoeStringGenealogy.com

[Adams]

Jennie,
When you review the above instructions, it will help if you make a list and put in the names that you know. Number from 1 to 10 vertically on a piece of paper. Next to number 1 write your name. Next to number 2 write your father's name. Next to number 3 write your mother's name. Next to number 4, write the name of your father's father. Next to number 5 write the name of your father's mother. Next to number 6 write the name of your mother's father. Next to number 7 write the name of your mother's mother. Who would be next to number 8? Your paternal great-grandfather. Next to number 9 would be his wife. Note that female names after #1 are always odd. male names are always even. Maybe this will help.
G Adams

[Barbara]

Dick, How do I number my maternal grandmother's, or any other ancestor's, siblings, their spouses, their children and grandchildren, etc.? It is necessary to research them to gather clues, fill-in the story of the family, or even find the direct line.

[Chris Carlson]

The beauty of this system is its simplicity and ease of use. It becomes obvious when you are reading someone else's genealogy work that uses this system. When you find the ancestor you are interested in, note their number. Twice that number will their father. Twice their number plus one will be their mother. It helps you wade easily through someone else's work. In addition, I labeled my hard copies of birth, death and marriage records with the ahnentafel number of the person in my direct line, additionally noting if this paperwork referred to a descendant of that person who was not in my direct line. I numbered children sequentially as 12-1, 12-2, etc. to indicate the offspring of person #12, my maternal great-grandfather. I labeled spouses 12-1A or B if there was more than one spouse. So my maternal great-grandfather's second daughter's second husband was 12-2B. For my Italian lines with many identical repeating names, this was a godsend.

[Dick Eastman]

---> Dick, How do I number my maternal grandmother's, or any other ancestor's, siblings, their spouses, their children and grandchildren, etc.?

You don't.

The word "ahnentafel" means "ancestor table," or a list of one's ancestors. It lists ONLY ancestors.

Your maternal grandmother's siblings, their spouses, their children and grandchildren, etc. are not your ancestors. They are relatives, but not ancestors.

- Dick Eastman

[Eileen Souza]

I can see why this system was useful but why do we need it today when our software calculates relationships? I can generate a relationship report or an ahnentafel report (which shows the numbers) from my software. Since it charts everyone in their proper place the numbers seem redundant.

[Loran Braught]

Ahnentafel numbering appears on most pedigree charts.

Extending those numbers to include descendants is an easy way to quickly and easily file or find collected documents for the descendants of any ancestor. For example, a grandfather is always numbered as #4. His children are numbered 4.1 (oldest child), 4.2 (second child), etc.

Having used this filing system for many years I recommend that it is efficient to number individuals married into your surname only for about three generations before creating a separate surname file for the "ancillary" surname family. For example, when I have data for my mother's grandparents (with liklihood of continued researching on her line), I create an entirely new family surname file and assign her the Ahnentafel number #1 in that new file.

Additionally, there is extended merit to applying the Ahnentafel system to all related documents and filing materials. For example, filing all vital documents (bith, marriage, death) in a manila file cabinet folder will soon become very bulky. Creating a three-ring notebook of vitals for each generation will simplify filing and finding those data. When vital documents for any of the children (for example, the oldest child 4c1 of paternal grandfather #4) pile up, just add a separate notebook with the ID number of 4c1.

The only challenge I have met with the Ahnentafel system has been for photo albums with group photos. I recommend assigning the Ahnentafel number of the oldest ancestor in the photo and cross-reference that number in the folder of the others. Because recent ancestors with many family photos, it is logically useful to create an album specifically for that generation (such as paternal grandfather #4 and his descendants).

No matter what organization numbering system is selected, the real key to organizing your piles into files is to commit regular hours per month exclusively to organizing (just as your local library staff does).

[Ned Smith]

Also, a couple tricks which can be helpful when you are dealing with very large ancestor tables- for each generation, the first male's number will tell you how many ancestral slots are in that generation. For instance the 5th generation will start with number 16, and there are 16 slots in that generation. For each generation the last females number will tell you how many total slots there have been in all generations up to that point. Again using the 5th generation as an example, the last female is number 31, and there are 31 total slots in the 1st, 2nd, 3rd, 4th, and 5th generations combined [and as a corollary, each generation has one more slot, than all the preceding generations combined.

Ned Smith

[Maddie]

Would someone just show the simple pronunciation of "ahnentafel" - I'm stumped.

[Nancy G.]

Maddie, Here is the pronunciation: [AH-nin-tah-ful]
In German the stress is almost always on the first syllable.

[Patricia]

I am trying to post numbers in FTM 2009. There is a place for reference numbers and Ahnentafel numbers. Which should I use?
Also, in Loran Braught's post on Sept. 22, 2008, a reference is made to "oldest child 4c1 of paternal grandfather #4)". I understand taht that 4.1 would refer to the paternal grandfather's 1st child, but what is the "c" for?
Thank you.
Patricia