Researching my 5th great grandmother, Sarah “Sally” Webb, opened a whole new line of Ancestors for me. So not only can I trace them back to ancient English Royalty and Scottish Kings, but they expose the potential of many famous and well-known people in my family. As I note on my page …of Cabbages and King, I find that I have a large number of Ancestors of reknown. To understand exactly how I am related to them, let’s how to calculate our relationships.

Cousin Relationships

We have all heard at some time that we have a cousin who is our 3rd cousin twice removed (of some such). So just what does that mean? A quick Google search will bring up many web sites that attempt to explain how this relationship is calculated. Most of them are so convoluted that they might as well be written in Latin. So I will try to take the mystery out of it with a simple formula. But first, an explananation…

First you must find a grandparent common to you and your cousin. That person will be your grandparent, great grandparent, great great grandparent, etc. Express this in terms of generations. That is, your great great great grandparent is your 3rd great grandparent, your great great grandparent is your 2nd great grandparent and and your great grandparent is your 1st great grandparent. It is as simple as expressing the generation as the number of “greats”.

Next, grandchildren of your grandparents are your first cousins and the great grandchildren of your great grandparents (1st great grandparents) are your 2nd cousins. From this we see that we have to account for your grandparents generation in the calculation. So if you both have the same generation great grandparents, then you a the generation +1 cousins. For example, if both of you have the same 3rd great grandparents you are 4th cousins (3rd +1).

Now for that squirrelly term “twice removed”. This term is used to explain the difference in the generations. In the last example, if the grandparent of your cousin is their 2nd great grandparent, you are once removed (3rd - 2nd). But removed from what? Your cousin relationship is based on the lower value of the generations. In this example, if your 3rd great grandparents are your cousins 2nd great grandparents, then you are 3rd cousins (2nd +1) once removed (3rd - 2nd).

See I told you it might as well be Latin!

Cousin Calculation Formula

So here is the simple formula I promised. Gen2 is taken as the larger generation value.:

Gen1 + 1 = Cousin, Gen2 - Gen1 = Times Removed

Not so difficult. Say grandpa Bob is your 5th great grandfather (Gen2) and he is also your cousin Jill’s 3rd great grandfather (Gen1). Then Jill is your 4th cousin (lesser of 5 and 3, plus 1), 2 times removed (5 - 3).

Cousin Calculator

So if you are math challenged (or just lazy like me) here is my Simple Cuz Calculator:

Cousin Calculator

If your common ancestor is your Parent 0
And your common ancestor is your relative’s Parent 0
Then you are Siblings