Two birthdays
- From
- 22 August 1985
- To
- 15 May 1990
Result4 years, 8 months and 23 days1,727 days in total
Working: From 22 August 1985, 4 whole years reach 22 August 1989 and 8 more months reach 22 April 1990. From 22 April to 15 May is 23 days.
Age Difference Calculator
The exact age gap between two dates in years, months and days, and who is older.
Enter two dates
Two birth dates, or any two dates, in either order.
Pick from the calendar, or type the date.
Pick from the calendar, or type the date.
How dates are counted: by calendar date only, so your time zone doesn't change the answer. Whole months are counted first, then the remaining days.
If a month is shorter than the start day, that month ends on its last day: 31 January plus one month is 28 February (29 in a leap year).
A 29 February birthday counts as 1 March in years without 29 February by default, as in Scotland's law; choose 28 February above if that is the rule you need.
What the calculator does
Enter two birth dates to see who is older and by how much, or any two dates to get someone's age on a given day, with total days, weeks and each next birthday.
- Clear date rulesMonth ends and 29 February explained
- Instant resultUpdates as soon as both dates are in
- Free, no sign-upNo account and no limits
- Stays on your deviceDates are calculated in your browser
Key points before you calculate
Whole months first, then days
A month without the matching day ends on its last day: 31 January + 1 month = 28 February (29 in a leap year).
29 February birthdays
Count as 1 March in other years by default, as in Scotland's law; 28 February is an option.
Dates only, no time zones
Your time zone and daylight saving time can't change the result.
Nothing is stored
The dates are calculated in your browser and are not sent to any server.
Step by step
How to use the age difference calculator
Enter two dates
Usually two birth dates, but any two dates work, in either order.
Read the difference
You get years, months and days, plus the totals in months, weeks, days and hours, and which date is earlier: the person born on it is older.
Use the extras
See the next birthday for each date, copy the result, or share a link that opens the calculator with the same two dates.
Age gap
What counts as an age gap
An age gap is the time between two people's dates of birth. Enter both birth dates and the calculator gives it in years, months and days. That gap stays the same however old the two people get.
When people ask how many years apart they are, they usually compare their current ages, and that number changes during the year. Someone born on 10 January 2000 and someone born on 20 June 2003 are 3 years, 5 months and 10 days apart.
From 10 January to 19 June each year
Their ages differ by 4
From 20 June to 9 January
Their ages differ by 3
Measurement only
The calculator only measures time between dates. It doesn't say whether an age gap matters, and it isn't legal advice about any age limit.
The rule
The calculation rule
The total number of days between two dates is the same everywhere. Splitting it into years, months and days needs a rule, and calculators don't all use the same one. This one works like this:
Whole months first, then days
From the earlier date, count as many whole months as fit before the later date (12 months make a year), then count the days that are left.
Short months end on their last day
When a month has no matching day, the month ends on its last day: one month after 31 January is 28 February, or 29 February in a leap year. Taiwan's Civil Code (Article 121) counts periods the same way.
29 February birthdays: 1 March by default, 28 February as an option
In years without 29 February, a 29 February birthday counts as 1 March. That is the rule written into Scotland's Age of Legal Capacity (Scotland) Act 1991. Other places count it as 28 February, and the law for England and Wales says only that an age is reached at the start of the birthday, so the calculator lets you switch to 28 February.
Dates only, no time zones
Dates are never turned into times of day, so your time zone and daylight saving time can't change the result. Leap years follow the Gregorian rule: every fourth year, except century years that can't be divided by 400 (2000 was a leap year, 1900 and 2100 are not). Total hours are simply the number of days × 24.
29 February birthdays: the two options side by side
| Question | 1 March (default) | 28 February (option) |
|---|---|---|
| First birthday after 29 February 2000 | 1 March (default)1 March 2001 | 28 February (option)28 February 2001 |
| 29 February 2000 to 28 February 2001 | 1 March (default)11 months and 30 days | 28 February (option)1 year |
| Basis | 1 March (default)Age of Legal Capacity (Scotland) Act 1991 | 28 February (option)Used in some other places |
Tip: match the rule you need
If an organisation counts a 29 February birthday as 28 February, choose that option under the Calculate button; the share link keeps the choice.
Worked examples
Worked examples
Each example is exactly what the calculator shows for these dates.
Siblings
- From
- 10 June 2018
- To
- 3 November 2020
Result2 years, 4 months and 24 days877 days in total
Working: 2 years reach 10 June 2020, 4 months reach 10 October 2020, and 10 October to 3 November is 24 days.
An age on a given day
- From
- 12 March 1999
- To
- 15 January 2024
Result24 years, 10 months and 3 days9,075 days in total
Working: Someone born on 12 March 1999 is 24 on 15 January 2024: 24 years reach 12 March 2023, 10 months reach 12 January 2024, then 3 days.
A month end
- From
- 31 January 2023
- To
- 1 March 2023
Result1 month and 1 day29 days in total
Working: One month after 31 January ends on 28 February, because February 2023 has no 31st. From 28 February to 1 March is 1 day.
A 29 February birthday
- From
- 29 February 2000
- To
- 28 February 2001
Result11 months and 30 days by default; 1 year with the 28 February option365 days in total
Working: With the default rule the first birthday is on 1 March 2001, so on 28 February 2001 the year isn't complete yet: 11 months reach 29 January 2001, then 30 days.
Quick reference
Age difference between two dates: quick reference
A few pairs of dates and what the calculator shows for them.
| Earlier date | Later date | Years, months, days | Total days |
|---|---|---|---|
| Earlier date10 Jan 2000 | Later date20 Jun 2003 | Difference3 years, 5 months, 10 days | Total days1,257 |
| Earlier date15 May 1990 | Later date2 Nov 1996 | Difference6 years, 5 months, 18 days | Total days2,363 |
| Earlier date8 Mar 1975 | Later date30 Sep 1988 | Difference13 years, 6 months, 22 days | Total days4,955 |
| Earlier date1 Jan 1990 | Later date1 Jan 2000 | Difference10 years exactly | Total days3,652 |
| Earlier date31 Jan 2023 | Later date1 Mar 2023 | Difference1 month, 1 day | Total days29 |
| Earlier date28 Feb 2100 | Later date1 Mar 2100 | Difference1 day2100 is not a leap year | Total days1 |
FAQ
Frequently asked questions
How do I calculate the age difference between two dates in years, months and days?
Start at the earlier date and count whole years, then whole months, without passing the later date; then count the days that are left. For 22 August 1985 and 15 May 1990: 4 years reach 22 August 1989, 8 more months reach 22 April 1990, and 23 days reach 15 May 1990, so the difference is 4 years, 8 months and 23 days. The calculator counts the same way and handles month ends and 29 February by the rules on this page.
Is an age gap calculator the same as an age difference calculator?
Yes. Age gap and age difference mean the same thing: the time between two people's dates of birth. This calculator also works for any two dates, so you can use it to find someone's age on a given day or the time between two events.
How do I find out who is older and by how much?
Enter both birth dates. The calculator says which date is earlier; the person born on that date is older, by the years, months and days shown. You can enter the dates in either order.
Why does 31 January to 1 March show 1 month and 1 day?
Whole months are counted first. February has no 31st, so one month after 31 January ends on the last day of February (28 February, or 29 in a leap year). From 28 February to 1 March is one more day. In 2023 that gives 1 month and 1 day, 29 days in total.
How are 29 February birthdays handled?
By default a 29 February birthday counts as 1 March in years without 29 February, which is the rule in Scotland's Age of Legal Capacity (Scotland) Act 1991. Some places count it as 28 February instead, so the calculator has a 28 February option. Someone born on 29 February 2000 turns 1 on 1 March 2001 by default, or on 28 February 2001 with the option.
Does my time zone change the result?
No. The calculator works with calendar dates only and never converts them to a time of day, so the same two dates give the same answer anywhere in the world and on both sides of a daylight saving change.
Can I use future dates or very old dates?
Yes, any date from the year 1 to 9999. A short note appears when a date is after today. Every date is treated as a date in today's Gregorian calendar, so a historical date recorded in another calendar has to be converted first.
Why might another calculator give a different answer?
The total number of days is the same everywhere, but the split into years, months and days depends on conventions: how a month that is too short for the start day is handled, and how 29 February birthdays are counted. This page states its rules next to the calculator so you can compare.
Can I rely on this for a legal age or an eligibility check?
Use it as a careful starting point, not as the final word. Laws and organisations set their own rules for when an age is reached, especially for 29 February birthdays, so check the rule that applies to your case.
Are the dates I enter stored anywhere?
No. The calculation runs in your browser and the dates are not sent to any server. If you use Share link, the two dates are part of the link, so anyone who has the link can see them.
Using a result for a legal age or an eligibility check?
Laws and organisations set their own rules for when an age is reached, especially for 29 February birthdays, so check the rule that applies to your case.
Sources
Sources
- Age of Legal Capacity (Scotland) Act 1991, section 6 (29 February birthdays count from 1 March)
- Family Law Reform Act 1969, section 9 (England and Wales: an age is reached at the start of the birthday)
- Civil Code of Taiwan, Article 121 (a period ends on the last day of the month when the day doesn't exist)
- NASA Glenn Research Center: leap years and century years divisible by 400
Written and checked by Ahmed Raza
Last reviewed:
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