Age Difference Calculator
Exact age gap between two birth dates in years, months, days and total days.
About this tool
Enter two names, which are only used as labels, and two birth dates. The calculator shows who is older and by how much in years, months and days, the total days and weeks between the dates, each person's age today, and how old the elder was when the younger was born.
How the age gap is counted
The difference is counted the way people count birthdays. First come whole months up to the last monthly anniversary, grouped into years, and then the remaining days. From 12 April 1990 to 30 September 1994 is 4 years, 5 months and 18 days, which is 1,632 days or about 233 weeks. Month ends are handled carefully. From 31 January to 1 March in a leap year is 1 month and 1 day, because one month after 31 January is taken as 29 February. The total in days includes every leap day. The gap itself never changes, but it matters less over time. Four years is a third of a twelve-year-old's life and only a twentieth of an eighty-year-old's. This works for partners, siblings, parents and children, colleagues or historical figures, as long as the dates are in the Gregorian calendar. The age calculator gives one person's exact age, the date difference tool counts between any two dates and life in weeks draws a lifetime as a grid. Leap years, explained properly explains the leap days.
Frequently asked questions
How do I calculate the age difference between two people?
Count whole months from the earlier birth date to the later one, group them into years, then count the remaining days. 12 April 1990 to 30 September 1994 is 4 years, 5 months and 18 days.
Does it count leap years?
Yes. The total in days includes every 29 February between the two dates.
Are the names stored?
No. Names and dates are used only on this page in your browser and nothing is stored or sent.
Can I compare dates before 1900?
Yes, for Gregorian calendar dates. Dates from before a country adopted the Gregorian calendar may need converting first.