Age Difference Calculator
Find the exact age gap between two people in years, months and days.
About the Age Difference Calculator
Enter two birth dates to find out exactly how much older one person is than the other, for siblings, couples, a parent and child, or two historical figures. The answer is given in years, months and days, in total days, and in decimal years.
The difference is counted in whole years, then whole calendar months, then leftover days, the same way ages are counted. The gap never changes over time: it is fixed by the two birth dates.
The formula
Age gap = later birth date − earlier birth date
Worked example
Born 14 March 1988 and 2 November 1992
- 14 March 1988 + 4 years = 14 March 1992
- + 7 months = 14 October 1992; + 19 days = 2 November 1992
- Gap: 4 years 7 months 19 days, which is 1,694 days or 4.64 years
Things to keep in mind
- Birth times and time zones are ignored, so two people born on the same date have a gap of 0 days even if hours apart.
- Month lengths differ, so a gap in months and days can look different from another tool that assumes 30-day months; the total in days is always exact.
Questions people ask
Does order matter?
No; the calculator works out who is older.
Can I compare more than two people?
Compare them in pairs; the gap between the oldest and youngest is the largest pair.
What's the “half your age plus seven” rule?
A social rule of thumb for dating, not a calculation this tool uses.