How to work out the day you outlive someone
Count the exact number of days the person lived, from their birth date to their death date. Add that number to your own date of birth, then add one more day. That is the first day you have lived longer than they did. Count in days, not years, so leap years are handled properly.
Step 1: count the days they lived
Start with the person’s date of birth and date of death. Albert Einstein was born on 14 March 1879 and died on 18 April 1955.
That is 76 full years, plus the 35 days from 14 March to 18 April 1955.
Step 2: add the leap days
Most years have 365 days. Leap years have 366.
The rule for leap years has three parts. A year divisible by 4 is a leap year. A year divisible by 100 is not, unless it is also divisible by 400.
So 1900 was not a leap year, but 2000 was. Einstein’s life included 18 leap days: every fourth year from 1880 to 1952, except 1900.
| Part | Days |
|---|---|
| 76 years of 365 days | 27,740 |
| Leap days (29 February) | 18 |
| 14 March to 18 April 1955 | 35 |
| Total | 27,793 |
Step 3: add the days to your birthday, plus one
Take your own date of birth and count forward 27,793 days. That is the day you draw level with Einstein.
The next day is the first one on which you have lived longer. For someone born on 1 January 1990, that is 5 February 2066.
Doing this by hand is slow, so let a computer count. Every person page on this site does it for you, for example Albert Einstein.
Why days beat years
Two people can both die “aged 76” and have lived different numbers of days. One might have died the day after a birthday, the other the day before the next.
Counting days also deals with leap years and 29 February birthdays without any special rules.
When the dates are uncertain
Our dates come from Wikidata. For many people born long ago, only the years are known. Those pages say “c.” and give a rough year rather than a date.
Old records are also sometimes disputed. If two sources disagree, the day you outlive someone can move by a day or more.
Common questions
Why add one extra day?
On the day your age in days equals theirs, you have only drawn level. The next day is the first one on which you have lived longer.
Why not just add their age in years to my birth year?
Years are different lengths. A 76-year life can contain 18 or 19 leap days, so counting in years can put you a day or two out.
What about people born on 29 February?
Counting in days avoids the problem. The number of days lived doesn't care which date the birthday falls on.
What if only the years are known?
For many people from the ancient world, only the birth and death years survive. Then the answer is a rough year, not a date.
Sources
Keep score on your phone
Outlived for iPhone tracks every famous person you outlive, tells you who is next, and gives you a nudge on the day.