Anniversary calculator, adding and subtracting days, months and years to date
Calculator computes what day is after adding (or subtracting) given number of days, months or years to your date. It can exclude Saturdays, Sundays and country-specific holidays from computations.

Beta version

This online calculator is currently under heavy development. It may or it may NOT work correctly.
You CAN try to use it. You CAN even get the proper results.
However, please VERIFY all results on your own, as the level of completion of this item is NOT CONFIRMED.
Feel free to send any ideas and comments !

Input data - start date and number of days to count

Start date
Number of days/months/years to add/subtract
Don't includeSaturdaysSundaysPublic holidays
Your region
(needed to adjust holidays list)

Results - dates of computed anniversaries

Start date2019-10-15 (Tuesday)
50 days later2019-12-04 (Thursday)
50 days before2019-08-26 (Monday)
50 months later2023-12-15 (Friday)
50 months before2015-08-15 (Saturday)
50 years later2069-10-15 (Tuesday)
50 years before1969-10-15 (Wednesday)
Days excluded while adding days (coming in the future)
Number of excluded saturdays
Number of excluded sundays
Number of excluded public holidays
Excluded public holidays
Total number of excluded days
Days excluded while subtracting days (from the past)
Number of excluded saturdays
Number of excluded sundays
Number of excluded public holidays
Excluded public holidays
Total number of excluded days
Anniversaries (days)
100 days anniversary2020-01-23 (Friday)
1000 days anniversary2022-07-11 (Tuesday)
100 days before2019-07-07 (Wednesday)
1000 days before2017-01-18 (Sunday)
Anniversaries (months)
100 months anniversary2028-02-15 (Tuesday)
1000 months anniversary2103-02-15 (Thursday)
100 months before2011-06-15 (Wednesday)
1000 months before1936-06-15 (Monday)
Anniversaries (years)
100 years anniversary2119-10-15 (Sunday)
1000 years anniversary3019-10-15 (Friday)
100 years before1919-10-15 (Wednesday)
1000 years before1019-10-15 (Friday)

Some facts

  • We may think, that adding or subtracting a few days (months, years) to (from) given date is a piece of cake. However, if we go deeper, we will find that there are many potential problems related to days arithmetic. Some months have 30, but other 31 days. Hey, but February has only 28 days! But, wait... once every four years February has 29 days. But which years are leap and which years are not? Argh! Maybe it will be easier to use Calculla?

What is the meaning of each calculator field ?

  • Start date - it is date used as reference to all further calculations. For example, if you want to know what date will be 50 days after Easter set this field to Easter day and number of days to 50.
  • Number of days/months/years to add/subtract - this is a number of days (months, years), which will be added (and subtracted) from your reference date set in "start date" field.
  • Don't include (Saturdays/Sundays/public holidays) - use this fields to exclude selected days from calculations. For example you can use this option if you want to count next 20 working days from today. In this case you should exclude all non-working days i.e.: Saturdays, Sundays and public holidays. This option is applied when shifting days only i.e. it doesn't affect result of adding/subtracing months or years.
  • Your region - this option is used only, when holidays exclusion is enabled (see "Don't include" field). Based on this field, Calculla will adjust list of known holidays to place where you live.

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Ancient version of this site - links

In December 2016 the Calculla website has been republished using new technologies and all calculators have been rewritten. Old version of the Calculla is still available through this link: We left the version 1 of Calculla untouched for archival purposes.
Direct link to the old version:
"Calculla v1" version of this calculator
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