Generation and age gap calculator
List relatives with their birth years or full dates. See the age gap between every pair, how long each generation took in your family, and how many years they shared.
Oldest to youngest
80.7 years
Edith to Lily: 80 years, 8 months and 13 days
Average generation
26.9 years
3 steps, from 25.2 years to 28 years
Everyone alive together
7.8 years
2012 to 2019
Generation by generation
- Edith → RuthEdith was about 25 years old
- Ruth → SamRuth was about 28 years old
- Sam → LilySam was 27 years, 6 months and 3 days old
Every pair
| Between | Age gap | Alive at the same time |
|---|---|---|
| Edith & Ruth | about 25 years | 63.4 years |
| Edith & Sam | 53 years, 2 months and 10 days | 35.4 years |
| Edith & Lily | 80 years, 8 months and 13 days | 7.8 years |
| Ruth & Sam | about 28 years | 42.3 years so far |
| Ruth & Lily | about 56 years | 14.8 years so far |
| Sam & Lily | 27 years, 6 months and 3 days | 14.8 years so far |
Lifelines
How many generations back?
About 9.2 generations, so up to 512 direct ancestors in that generation.
Reading the results
With two full dates, the age gap is exact to the day. When a date is only a year, the calculator assumes the middle of that year and shows an approximate gap, accurate to about a year either way. Anyone without a death date counts as living, unless they would now be over 120; then their lifeline stops with a question mark.
Tick “line of descent” when each person is the child of the one above, such as great-grandmother, grandmother, mother and daughter. The gap between births is then the parent’s age when the child was born, and the average of those steps is your family’s generation length along that line.
How long is a generation?
A 2023 study estimated an average human generation time of 26.9 years over the past 250,000 years, with fathers older on average (30.7 years) than mothers (23.2 years). A cross-cultural study in 2005 also found male generation intervals substantially longer than female ones. Genealogists often use 25 to 33 years as a working range, which is why the generations-back estimate lets you choose.
The number of ancestors doubles each generation on paper, but in real families the same people appear on several branches (pedigree collapse), so the true count is smaller.
Sources
- Wang RJ, Al-Saffar SI, Rogers J, Hahn MW. Human generation times across the past 250,000 years. Science Advances 2023;9(1):eabm7047. doi:10.1126/sciadv.abm7047
- Fenner JN. Cross-cultural estimation of the human generation interval for use in genetics-based population divergence studies. American Journal of Physical Anthropology 2005;128(2):415–423. doi:10.1002/ajpa.20188
Questions
Are the names and dates saved?
Yes, in your browser’s local storage only, so they are still here next time. They are never sent anywhere. Press Clear to remove them.
Why does a year-only date say “about”?
Born in 1956 could mean January or December, so a gap between two years can be off by up to a year. Add the month and day for an exact answer.
Can I use dates before 1752?
Yes, but dates are counted on today’s Gregorian calendar. Records from before a country switched calendars may be Julian dates, which run 10 to 13 days behind.