Age Gap Calculator
Find the age gap between two people — enter both dates of birth to get the age difference in years, months and days, plus the “half your age plus seven” guide.
How to calculate the age gap between two people
The age gap is simply the difference between two birth dates. Enter both dates of birth above and the calculator subtracts the earlier from the later and shows the gap in years, months and days, handling leap years and the different month lengths for you. It also gives the total in days and decimal years.
The order does not matter — the calculator always reports the gap as a positive difference. The same tool answers “age difference” questions: how far apart two people, two events or two milestones are in time.
The “half your age plus seven” rule
A long-standing social rule of thumb for the youngest “acceptable” partner age is to take half your age and add seven. So a 40-year-old’s minimum would be 27 (40 ÷ 2 + 7), and a 30-year-old’s would be 22. The calculator shows this guide for the older person. It is a cultural heuristic, not a law or a scientific finding — treat it as a conversation starter, not a rule.
Whether a gap feels “big” depends a lot on age: seven years between two people in their 40s is usually unremarkable, while the same gap at much younger ages is more significant. For one person’s exact age, use the chronological age calculator.
Frequently asked questions
How do I calculate the age difference between two people?
Subtract the earlier date of birth from the later one and express the result in years, months and days. The calculator does the date arithmetic — including leap years — so you get the exact gap from the two birth dates you enter.
What is the “half your age plus seven” rule?
It is a rule of thumb for the minimum “acceptable” partner age: take half your age and add seven. So a 30-year-old’s minimum would be 22 (30 ÷ 2 + 7). The calculator shows this guide for the older person — it is a social heuristic, not a law or scientific rule.
Is a 7-year age gap big?
There is no fixed answer — it feels larger at younger ages than older ones. A 7-year gap between two people in their 40s is often unremarkable, while the same gap involving someone very young can be significant. The calculator gives the exact difference so you can judge for yourself.