For a true "relationship" to exist, there must be an ancestor who is common to both individuals. In the chart below, the Common Ancestor is Box 1 on the horizontal scale as well as Box 1 on the vertical scale.

Let us suppose that you have a grandson of that common ancestor, as seen in Box 3 of the horizontal scale, and you want to know that grandson's relationship to a great-granddaughter, who would be seen in Box 4 on the vertical scale.

If you follow Box 4 (Vertical Scale) down to where it meets the vertical pathway to Box 3 on the horizontal scale, then where those paths cross, it tells you the relationship -- they are first cousins once removed.

	1	2	3	4	5	6	7	8	9	10
1	Common Ancestor	Son or Daughter	Grandson or Daughter	Great Grandson or Daughter	2nd Great Grandson or Daughter	3rd Great Grandson or Daughter	4th Great Grandson or Daughter	5th Great Grandson or Daughter	6th Great Grandson or Daughter	7th Great Grandson or Daughter
2	Son or Daughter	Siblings (Brother or Sister)	Nephew or Niece	Grand Nephew or Niece	Great Grand Nephew or Niece	2nd Great Grand Nephew or Niece	3rd Great Grand Nephew or Niece	4th Great Grand Nephew or Niece	5th Great Grand Nephew or Niece	6th Great Grand Nephew or Niece
3	Grandson or Daughter	Nephew or Niece	First Cousin	First Cousin Once Removed	First Cousin Twice Removed	First Cousin Three Times Removed	First Cousin Four Times Removed	First Cousin Five Times Removed	First Cousin Six Times Removed	First Cousin Seven Times Removed
4	Great Grandson or Daughter	Grand Nephew or Niece	First Cousin Once Removed	Second Cousin	Second Cousin Once Removed	Second Cousin Twice Removed	Second Cousin Three Times Removed	Second Cousin Four Times Removed	Second Cousin Five Times Removed	Second Cousin Six Times Removed
5	2nd Great Grandson or Daughter	Great Grand Nephew or Niece	First Cousin Twice Removed	Second Cousin Once Removed	Third Cousin	Third Cousin Once Removed	Third Cousin Twice Removed	Third Cousin Three Times Removed	Third Cousin Four Times Removed	Second Cousin Five Times Removed
6	3rd Great Grandson or Daughter	2nd Great Grand Nephew or Niece	First Cousin Three Times Removed	Second Cousin Twice Removed	Third Cousin Once Removed	Fourth Cousin	Fourth Cousin Once Removed	Fourth Cousin Twice Removed	Fourth Cousin Three Times Removed	Fourth Cousin Four Times Removed
7	4th Great Grandson or Daughter	3rd Great Grand Nephew or Niece	First Cousin Four Times Removed	Second Cousin Three Times Removed	Third Cousin Twice Removed	Fourth Cousin Once Removed	Fifth Cousin	Fifth Cousin Once Removed	Fifth Cousin Twice Removed	Fifth Cousin Three Times Removed
8	5th Great Grandson or Daughter	4th Great Grand Nephew or Niece	First Cousin Five Times Removed	Second Cousin Four Times Removed	Third Cousin Three Times Removed	Fourth Cousin Twice Removed	Fifth Cousin Once Removed	Sixth Cousin	Sixth Cousin Once Removed	Sixth Cousin Twice Removed
9	6th Great Grandson or Daughter	5th Great Grand Nephew or Niece	First Cousin Six Times Removed	Second Cousin Five Times Removed	Third Cousin Four Times Removed	Fourth Cousin Three Times Removed	Fifth Cousin Twice Removed	Sixth Cousin Once Removed	Seventh Cousin	Seventh Cousin Once Removed
10	7th Great Grandson or Daughter	6th Great Grand Nephew or Niece	First Cousin Seven Times Removed	Second Cousin Six Times Removed	Third Cousin Five Times Removed	Fourth Cousin Four Times Removed	Fifth Cousin Three Times Removed	Sixth Cousin Twice Removed	Seventh Cousin Once Removed	Eighth Cousin