What is our age difference?
Calculate age difference between two people or dates. Personal and relationship calculator.
- Age difference
- 0 days
Person 1 and Person 2 are the same age; the age gap is 0 days.
- Who is older
- Person 1 and Person 2 are the same age
- Total days
- 0
- Total weeks
- 0 days
- Total months
- 0
Answer for the example date Monday, October 5, 2026. It changes to today's date when the page loads.
Age difference: 0 days. Person 1 and Person 2 are the same age; the age gap is 0 days.
When was each person born?
How to calculate
Works out the gap between two birth dates in years, months, and days, the total days, and who is older.
Example with the default inputs (First person’s birth date October 5, 2026, Second person’s birth date October 5, 2026) on the example date Monday, October 5, 2026: Person 1 and Person 2 are the same age; the age gap is 0 days.
Method: From the earlier birth date, count whole years while the later birth date is not passed, then whole months, then the days left.
- A month is counted when the same day of the month is reached; when that month is shorter, its last day counts (January 31 plus one month is February 28, or 29 in a leap year).
- A year from February 29 ends on February 28 in a common year.
- The difference is the same whichever person is entered first.
- Dates are calendar days with no time of day or time zone.
Worked examples
Each example is checked against the calculator on every build.
- First person’s birth date 1990-05-15, Second person’s birth date 1995-08-20 gives Age difference 5 years, 3 months, 5 days, Who is older Person 1 is older than Person 2, Total days 1,923, Total months 63.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years
- First person’s name Ann, First person’s birth date 2010-06-01, Second person’s name Bob, Second person’s birth date 1970-06-01 gives Age difference 40 years, Who is older Bob is older than Ann, Total days 14,610, Total weeks 2,087 weeks, 1 day.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years
- First person’s birth date 2024-02-29, Second person’s birth date 2025-03-01 gives Age difference 1 year, 1 day, Total days 366.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years
- First person’s birth date 1999-12-31, Second person’s birth date 1999-12-31 gives Age difference 0 days, Who is older Person 1 and Person 2 are the same age, Total days 0.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule. https://aa.usno.navy.mil/faq/leap_years
How it works
Take the two birth dates as calendar days in the Gregorian calendar, with no time of day. Call the earlier one A and the later one B; the order you enter them in does not change the difference.
- Years. The most whole years Y such that A plus Y years is on or before B.
- Months. From A plus Y years, the most whole months M (0 to 11) such that the same day of the month, M months later, is on or before B.
- Days. The days left to B.
When a month does not have A’s day of the month, the month’s last day counts instead: one month after January 31 is February 28 (or 29 in a leap year), and one year after February 29 is February 28 in a common year.
Other results.
- Who is older: the person with the earlier birth date. With the same date, they are the same age. Without names, the people are called Person 1 and Person 2.
- Total days: B − A in whole days.
- Total weeks: the total days as whole weeks and the days left.
- Total months: 12 × Y + M.
Assumptions
- A month is counted when the same day of the month is reached, with month ends clamped as above.
- Dates have no time of day or time zone.
Worked examples by hand
May 15, 1990 and August 20, 1995. Person 1 is older. From May 15, 1990, 5 years reach May 15, 1995, 3 months reach August 15, 1995, and 5 days reach August 20: 5 years, 3 months, 5 days, or 5 × 12 + 3 = 63 months. Total days: 1,923.
Ann (June 1, 2010) and Bob (June 1, 1970). Bob is older, by exactly 40 years. Total days: 40 × 365 plus the 10 leap days from 1972 to 2008 = 14,610, which is 2,087 weeks and 1 day.
February 29, 2024 and March 1, 2025. One year after February 29, 2024 is February 28, 2025 (2025 is not a leap year), and March 1 is one day later: 1 year, 1 day. Total days: 366.
The same birth date twice. The difference is 0 days, and the two people are the same age.
Other questions people ask
How does the Age Difference Calculator work?
The Age Difference Calculator calculates the precise difference between two birth dates in years, months, and days. It determines which person is older and shows the exact time difference between their birth dates.
Can I calculate age difference between any two dates?
Yes, you can calculate the age difference between any two birth dates. The calculator works with dates from the past, present, and even future dates for planning purposes.
What if both people have the same birth date?
If both people have the same birth date, the calculator will show that they are the same age with no difference in years, months, or days.
How accurate is the age difference calculation?
The calculation is very accurate, taking into account leap years, varying month lengths, and precise day counting. It provides the exact difference in years, months, and days between two birth dates.
Can I use this calculator for planning events?
Yes, this calculator is perfect for planning events where age differences matter, such as birthday parties, family gatherings, or understanding generational gaps between family members.
What information do I need to use the calculator?
You need the birth dates of both people. You can also optionally add names for each person to personalize the results. The calculator will automatically determine which person is older.
How is the age difference displayed?
The age difference is displayed in a clear format showing years, months, and days. For example: '2 years, 3 months, 5 days'. The calculator also shows which person is older, the total days, weeks, and months between the birth dates.
Can I calculate age differences for historical figures?
Yes, you can use this calculator to compare birth dates of historical figures, celebrities, family members, or anyone whose birth date you know. Dates follow the Gregorian calendar, so for births recorded in the Julian calendar (before 1582 in most of Europe, later elsewhere) convert the dates first.
Is this calculator free to use?
Yes, the Age Difference Calculator is completely free to use. You can calculate as many age differences as you need without any cost or registration required.
What are some practical uses for this calculator?
This calculator is useful for understanding family relationships, planning age-appropriate activities, comparing life milestones, genealogical research, and general curiosity about age differences between people.