Dates & Time

Age Difference Calculator (Gap Between Two Birthdates)

Enter two birthdates and you get the gap between them in years, months, and days. It also totals the days between the two people and applies the half-your-age-plus-seven rule to the older person.

How to use
  1. Enter the first person's date of birth.
  2. Enter the second person's date of birth.
  3. Check the half-your-age-plus-seven figure for the older person.
Example gap
Age difference
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Decimal years
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Total months
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Total weeks
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Total days
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Half age + 7 (older)
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Date math uses your inputs as given; check time-zone and leap-year edge cases.
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How it's calculated

age gap = | date of birth A − date of birth B |

Difference between two birth dates, shown in years/months/days and total days. Decimal years = total days ÷ 365.2425; the “half-your-age + 7” social rule is also displayed.

Common questions

Does the order of the dates matter?

No. The calculator works out which person is older on its own and reports the gap the same way either direction.

What is the half-your-age-plus-seven rule?

It is a rough social guideline for the youngest age someone is often considered an appropriate partner: take half the older person's age and add seven.

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