How many ancestors do I have?
You have 2 parents, 4 grandparents and 8 great-grandparents. Every generation back, the number doubles. Slide to see how fast it grows.
The quick table
| Generation | Who they are | In that generation | Total so far |
|---|---|---|---|
| 1 | Parents | 2 | 2 |
| 2 | Grandparents | 4 | 6 |
| 3 | Great-grandparents | 8 | 14 |
| 4 | 2× great-grandparents | 16 | 30 |
| 5 | 3× great-grandparents | 32 | 62 |
| 6 | 4× great-grandparents | 64 | 126 |
| 7 | 5× great-grandparents | 128 | 254 |
| 8 | 6× great-grandparents | 256 | 510 |
| 9 | 7× great-grandparents | 512 | 1,022 |
| 10 | 8× great-grandparents | 1,024 | 2,046 |
The formula: generation g holds 2g people, and all generations up to g add up to 2g+1 − 2.
How far back is that?
A generation averages roughly 25–30 years. Your 10th generation lived about 250–300 years before you were born, which for most people today means the early-to-mid 1700s. That's around when many family lines first show up in parish registers and colonial records.
Why the real number is smaller: pedigree collapse
Go back 30 generations and the doubling gives over a billion ancestors, more people than were alive in Europe at the time. The answer is pedigree collapse: distant cousins married each other, so the same person appears in several places on your tree. Everyone's tree narrows this way further back. In small or isolated communities it can start within just a few generations.
See your own numbers
Load your GEDCOM file into Fan Chart Studio and it shows how many ancestors you've found, drawn as a fan chart with a ring for each generation. The gaps are the ancestors still waiting to be discovered.
Map your ancestors on one page
Up to 10 generations, 1,023 people, in a chart you can frame.
Make your fan chart