Age difference calculator
The exact gap between two birthdays — for siblings, couples, or settling an argument.
Enter both birth dates.
Questions
How do you calculate the age difference between two people?
Take the earlier birth date and count forward to the later one: whole years first, then whole months, then the remaining days. The result is the same no matter what date you calculate it on.
Does the age gap change over time?
The gap in years, months and days never changes. What changes is how big it feels: a 10-year gap is half the younger person's life at 20, but only 1/7 at 70.
What is the "half your age plus seven" rule?
It is a popular rule of thumb for the youngest socially acceptable partner age: half the older person's age plus seven years. It is a joke-rule, not a law or a scientific standard.
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