Genealogy Date Calculator
Estimate birth years and ages for ancestors when records are incomplete. Uses standard genealogical generation lengths and historical life expectancy data.
Estimates are based on average genealogical generation lengths and historical demographic data. Individual family histories vary significantly. Use primary source records (birth certificates, census records, church registers) whenever available.
Genealogical Generation Lengths
The average genealogical generation length — the average age of parents at the birth of their children — has varied throughout history. Before 1900, the average was approximately 25–28 years in Western countries. Today it is closer to 28–32 years. Using 28 years as a standard estimate means your great-grandparents were born approximately 84 years before you.
Keep in mind that generation lengths vary widely within families. Some families had children young (at 18–20), others late (at 35–40). When estimating ancestor birth years, always cross- reference with census records, church registers, and death certificates when available.