What is an age gap?

The age gap between two people is the time between their birth dates. Subtracting ages gives a rough answer that changes during the year: between the two birthdays, the ages differ by one more than at other times. Counting from one birth date to the other gives the exact gap, and it never changes.

The "half your age plus seven" rule is a well known rule of thumb for the youngest partner who isn't too young for you. Halve your age and add seven: at 36 that's 18 + 7 = 25. It is a social rule of thumb, not a law.

Tool description

Enter the birth dates of Person 1 and Person 2. The tool shows:

  • The age gap in years, months and days, and in total days
  • Who is older
  • Each person's age today, in whole years
  • The youngest partner age for each person by the half your age plus seven rule, and whether the other person passes it

The rule checks both ways. The older person nearly always passes the younger one's rule, so the check that matters is the younger person against the older one's.

Years and months count like birthdays: a month is complete when the same day of the month comes round again. Someone born on February 29 turns a year older on March 1 in years without a leap day.

Example

Person 1 born on March 15, 1990 and Person 2 born on July 2, 1998:

  • Age gap: 8 years, 3 months and 17 days, or 3,031 days
  • Person 1 is older
  • On November 10, 2026 they are 36 and 28
  • The youngest partner for 36 is 25, so Person 2 passes. The youngest for 28 is 21, so Person 1 passes too

Features

  • Exact age gap in years, months, days and total days
  • Both people's current ages
  • Half your age plus seven check for both people