Date Difference & Age Calculator
Pick two dates to see the calendar difference, the total in days and weeks, and the number of Monday-to-Friday business days. Switch to Age to work out how old someone is on any date, when their next birthday falls and which weekday they were born on. All of the arithmetic is done on this page.
Exclude holidays from business days
How to use
- Choose Between two dates, then set the start and end dates (the Today buttons fill in today's date; Swap dates reverses them).
- Tick Include end date if the last day should count as a full day, for example when counting the length of a booking or a leave period.
- Tick Include times to add a start and end time; the result then shows hours and minutes too.
- To leave public holidays out of the business-day count, open Exclude holidays and enter one YYYY-MM-DD date per line.
- For an age, choose Age, enter the date of birth and, if needed, a different Age at date. Then use Copy summary to copy the result as plain text.
Examples
1 month, 1 day · 30 days in total (2024 is a leap year)
0 months, 28 days · 4 weeks exactly
1 year · 365 days = 52 weeks and 1 day
7 business days (10 weekdays, minus 3 holidays; end date not counted)
26 years, 7 months, 8 days with the 1 March rule (next birthday Monday, 1 Mar 2027, in 143 days), or 26 years, 7 months, 10 days with the 28 February rule. Born on a Tuesday.
Supported formats
- Dates from 1 January 0001 to 31 December 9999 in the proleptic Gregorian calendar (the Gregorian rules applied to all years, including those before 1582).
- Holiday lists: one date per line in YYYY-MM-DD form; anything after the date on the same line (such as a holiday name) is ignored, and lines starting with # are skipped.
- Output: years, months and days; total days; weeks and days; business days (Monday to Friday); with times, hours and minutes too.
Privacy
This tool runs entirely in your browser. Nothing you enter or open is sent anywhere. Privacy policy.
Limitations
- Gregorian calendar only. Historical dates are not converted from the Julian calendar, so dates before a country adopted the Gregorian calendar (1582 to 1923, depending on the country) will not match the records of the time.
- Date-only results are pure calendar arithmetic and ignore time zones. With times, the elapsed hours use your device's time zone. If a daylight-saving change falls in the range, the page says so and shows real elapsed time, which differs from the clock-face difference by the size of the shift.
- Business days are always Monday to Friday. No public holidays are built in; only the dates you type in are excluded, and different weekend patterns (such as Friday–Saturday) are not supported.
- Months vary in length, so a difference such as "1 month, 1 day" depends on the convention used. This tool's convention is described in the FAQ; other calculators may give a different answer for ranges that start near the end of a month.
FAQ
Why does 31 January to 28 February show 28 days, not 1 month?
A whole month is counted only when the end date reaches the same day of the month as the start date. 28 February comes before the 31st, so the answer is 28 days. If the start day does not exist in a month (the 31st in February, for example), the month anniversary falls on that month's last day. So 31 January to 1 March is 1 month (to 28 or 29 February) plus 1 day. This is the same convention as Java's Period.between.
Is the start or end date counted?
By default, the result is the number of days from the start date up to the end date, so Monday to Friday is 4 days. Ticking Include end date adds the final day (Monday to Friday becomes 5 days). Business days count the same span: the start date is always included, and the end date only when that box is ticked.
How are 29 February birthdays handled?
In years without 29 February, you choose whether the birthday falls on 28 February or 1 March. The setting changes when the age goes up and from which date the extra months and days are counted. The total number of days lived is the same either way. Different countries' laws use different rules, so pick the one that applies to you.
What happens if the end date is before the start date?
The tool shows the size of the gap, measured from the earlier date to the later one, and adds a note that the range is reversed. The result box shows a minus sign so you can tell it apart from a forward range.