Age Difference Calculator

Enter First person's date of birth and Second person's date of birth, add names if you like, and press Calculate. The first line of the result is the direct answer, for example "Anna is 2 years, 8 months and 21 days older than Ben." Below it, the table breaks the gap down.

For birth dates of May 20, 1990 (Anna) and February 10, 1993 (Ben):

Age gap is the calendar difference, the way people usually say it. Total months counts only whole months, and Total weeks only whole weeks, so leftover days are dropped from both. Total days is the exact number of days between the two birth dates.

The last two rows show each person's age on today's date. On October 8, 2026, Anna was 36 years, 4 months and 18 days old and Ben 33 years, 7 months and 28 days.

The names are optional. Leave them empty and the answer uses Person A and Person B instead. The table can be copied or exported as CSV, XLSX, PDF or an image.

Subtracting birth years gives a rough idea of an age gap, but it can be off by almost a full year in either direction. Two people born in consecutive years might be one day apart or nearly two years apart. The month and the day decide.

In the first row the two people share a school year in many countries and celebrate their birthdays one day apart. In the third row they are 729 days apart, which is closer to two years than to one.

This is why the calculator asks for full dates. A gap stated in years, months and days is the figure you can compare with confidence, and the total days row removes any doubt about month lengths.

The calculator always starts from the earlier birth date, so it does not matter which person you enter first. It then adds whole months until the next step would pass the later birth date, and counts the days that remain.

When the starting day does not exist in a month, it moves to that month's last day. Compare January 31, 1988 with March 1, 1988: one month after January 31 lands on the last day of February, February 29 in that leap year, and one more day reaches March 1. The gap is 1 month and 1 day, a total of 30 days.

The other rows are simpler:

• Total days is the exact difference between the two dates.
• Total weeks is total days divided by seven, rounded down.
• Total months is the years of the gap times twelve plus its months.

The gap itself never changes. Two people born 997 days apart stay 997 days apart for life, and only their current ages move forward. What can feel different over time is the proportion: a three-year gap is large between a child of two and a child of five, and barely noticeable at forty and forty-three. The calculator shows the fixed gap, and the current age rows let you see where both people stand today.

February 29 exists only in leap years: years divisible by 4, except century years that are not divisible by 400. The calculator follows these Gregorian rules, so a birth date of February 29 is handled like any other date, with one detail worth knowing.

One year after February 29, 2000 would fall on February 29 in 2001, a date that does not exist. In a common year, the full year is reached only on March 1, which is also the day on which most date tools and many legal systems count a leap-day birthday as passed.

The first row can look surprising, since 365 days is usually a year. It is not a full year here because the leap-day birthday has not yet come round in 2001. If you prefer a single unambiguous figure for a leap-day comparison, use Total days.

People look up age gaps for all kinds of reasons, and the calculator does not judge any of them. It does arithmetic and nothing else.

• Couples and friends use it out of curiosity, or to settle who is older when two birthdays are close.
• Siblings and cousins can be compared to the day, which is handy for family trees and anniversary cards.
• Twins born on the same date get the answer that they are the same age. Births on either side of midnight show a gap of 1 day, even if the real difference was a few minutes, because the tool works with dates, not times.
• Writers can check the ages of characters against a timeline so a sibling is not accidentally younger in chapter ten than in chapter two.
• Genealogy work often involves comparing the ages of relatives listed in old records.

To compare more than two people, run the calculator in pairs. With three siblings, comparing the eldest with each of the others gives every gap you need.

A few related tools cover nearby questions. For one person's exact age on any date, use the age calculator. To count the days between any two dates, not only birth dates, try a days-between-dates calculator. A birth year calculator works out a birth year from an age, and a birthday countdown shows how long it is until the next birthday.

Names and birth dates are personal data, so the calculator handles them on your device only. Everything is calculated in your browser, and nothing you type is uploaded, logged or stored. Reloading the page clears it.

The tool is free, needs no account or sign-up, and has no limit on how many comparisons you run. Results export as CSV, XLSX, PDF or an image without a watermark, which makes it easy to keep a record for a family tree or share a result in a message.