Date calculator: difference, duration, age, countdown, working days
Six modes in one tool: days between dates, human-readable duration, add or subtract, age, countdown, and German working days.
A date calculator answers more than one question: how many days lie between two dates, what is a date plus 90 days, how old are you in months - and how many working days remain until a deadline? Pick one of six modes at the top. The date modes compute on a calendar-day basis, with ISO week numbers and German public holidays per state; only the countdown runs in real time.
How many days, weeks, months and years lie between two dates?
30 Days equals 4.3 weeks, 1.0 months, 0.08 years.
Note. All calculations work on a calendar-day basis without timezone conversion. For cross-timezone work, a dedicated timezone tool is the better fit.
How many days between two dates?
Enter both dates in Difference mode. Days are counted as exact calendar days, with no rounding across month boundaries. From 18 May to 24 December 2026 that is 220 days, and the same span also appears converted to weeks, months, and years.
| Unit | Result |
|---|---|
| Days | 220 |
| Weeks | about 31.4 |
| Months | about 7.2 |
| Years | about 0.6 |
The week, month, and year figures are conversions using average lengths (a month counts as 30.44 days, a year as 365.2425). If you want the calendar-correct decomposition instead, use Duration mode: for the same span it returns "7 months and 6 days" - the way you would say a deadline or project length out loud.
How many working days is that?
Working-days mode counts the weekdays between two dates and subtracts weekends and public holidays. Because German holidays are set per state, you pick your Bundesland (federal state) - all 16 are included with their state-wide holidays. Start and end date both count, so the range is inclusive.
Three rules drive the result:
- Saturdays and Sundays are always excluded.
- A holiday only subtracts when it falls on a weekday. A holiday on a Sunday is not subtracted twice - the calculator points these cases out.
- The holiday table covers the state-wide statutory holidays under current rules, including Berlin's one-off commemoration holidays (8 May 2025, 17 June 2028). Municipal special cases like Augsburg's Friedensfest are not included; for years far in the past the table is also less reliable.
The difference is measurable: in November 2026, Berlin counts 21 working days but Saxony only 20, because the Day of Repentance and Prayer (18 November) is a public holiday there alone. For planning a full year with vacation and sick days, there is the Working-days calculator - it draws on the same holiday table as this mode. And for daily and weekly hours with breaks, the Working-time calculator takes over.
How do I calculate my age in years, months, and days?
Enter your birth date in Age mode. You get your age as calendar-correct years, months, and days, plus the totals in weeks and hours. The method counts whole calendar months first - as many as fit into the span - and then the remaining days.
Almost every age calculator uses this convention, but it has an edge case: anyone born on 29 February has no calendar birthday in three out of four years. The calculator then treats 28 February as the anniversary and shows a hint - German legal practice sometimes uses 1 March, depending on context. And on the day before your birthday you are still at 11 months and some days: the age only ticks over once the year is complete.
How many days until Christmas?
Set Countdown mode to 25 December (or 24 December if Christmas Eve is your moment) and the remaining time ticks live: days, hours, minutes, and seconds until midnight (0:00) at the start of the target day. The same works for any deadline: a submission date, a holiday, the end of a contract.
To get more out of the mode:
- "Share link" saves the countdown with its target date as a URL - handy as a bookmark or to send around.
- The pause button freezes the display; in a background tab it pauses by itself and spares your battery.
- If the date is already in the past, the calculator tells you how many days ago it was and suggests Difference mode.
How do I add 90 days to a date?
Add mode computes a date plus or minus a number of days, weeks, months, or years. Days and weeks are exact day arithmetic. With months and years the target day can be missing - 31 January plus one month lands in February, which only has 28 or 29 days.
Such overflows are explained rather than silently rounded: the result moves to the last day of the target month (end-of-month convention), and a hint tells you why. 29 February 2024 plus one year lands on 28 February 2025 this way, with an explanation instead of silence. One thing to know: the mode adds calendar days, not business days - if you need "90 days, but only weekdays", check the span in Working-days mode afterwards. And if you need seconds since 1970 rather than calendar dates, the Unix timestamp converter translates both ways.
Frequently Asked Questions
What does the ISO week number next to my date mean?
ISO-8601 weeks start on Monday, and week 1 is the week containing the year's first Thursday. Around the turn of the year a date can therefore belong to the previous or next year's week: 1 January 2027, for example, still sits in week 2026-W53. The calculator shows the week number for both dates and adds a hint at those boundary cases.
What happens if the end date is before the start date?
In Difference mode you get a negative result plus a hint - not an error, you can simply swap the dates. Duration and Working-days mode order the two dates themselves, so the order does not matter there. A countdown to a past date tells you how many days ago it was.
Does the date calculator handle time zones?
No. The date modes work on a calendar-day basis without timezone conversion - daylight saving never shifts those results. Only the countdown runs in real time until midnight of the target day: across a DST switch, its hour display can therefore differ by one hour from the plain day count. For Unix timestamps or time zones, a dedicated tool is the better fit.