Age Difference Calculator
The exact age gap between two people, in years, months and days.
Good to know. An age gap never changes, but it matters less every year: 5 years is a lot at 10 and very little at 50.
How it works
In plain words
Count from the earlier date of birth to the later one: whole years first, then whole months, then the days left over. The total in days is the plain count of days between them.
The formula
gap = later date − earlier date, in calendar years, months and days
Worked example
Born on 14 May 1990 and 2 November 1994, two people are 4 years, 5 months, 19 days apart, or 1,633 days.
Sources
No outside data or rates: this is plain arithmetic.
3 automated tests check its answers on every change.
About the age difference calculator
The age difference between two people is the time between their dates of birth. It stays the same all their lives, which is why it is easiest to work out from the birthdays rather than from their current ages, which can be a year out depending on whose birthday has passed.
The gap is counted the way ages are: in whole years, then whole months, then days. From 14 May 1990 to 2 November 1994 is 4 years to 14 May 1994, 5 months to 14 October, and 19 more days. The total in days is useful for exact comparisons, and the decimal years for a quick sense of scale.
People look up age gaps for siblings, couples, parents and children, or teammates. In couples, a popular rule of thumb says the younger partner should be at least half the older one’s age plus seven. It is a curiosity, not a measure of anything that matters.
For one person’s exact age today, use the age calculator. For the days between any two dates, not just birthdays, the days between dates calculator.
Questions people ask
How do I calculate the age difference between two people?
Count from the earlier date of birth to the later one, in years, months and days. The calculator does the counting.
Why does the age difference seem to change during the year?
Comparing current ages can be off by one between the two birthdays. The gap between the dates of birth never changes.
What is the half-your-age-plus-seven rule?
A saying that the younger partner should be at least half the older one’s age plus seven. It is folklore, not science.