About
Last updated: 2026-06-25
Anniversary Calculator is a free collection of tools for couple 100/1000 days, anniversary D-day, and wedding anniversaries.
All calculations run in your browser, and we publish our date counting rules transparently.
What is Anniversary Calculator
Anniversary Calculator is a free set of tools that helps couples, spouses, and families count the special dates they cherish quickly and accurately. You can calculate 100 and 1000 days of dating, the D-day to a specific anniversary, and a wedding anniversary year and its name right in your browser, with no sign-up or install.
Operating principles (E-E-A-T)
- Experience — We reflect the way anniversaries are actually celebrated, such as day-one-inclusive counting and names like silver and golden anniversaries.
- Expertise — We clearly define our calculation rules: day-one-inclusive vs exclusive counting, year calculation by the same calendar month and day, and traditional wedding anniversary names.
- Authoritativeness — For parts that can vary by source, such as wedding anniversary names, we make clear that these are commonly used conventions.
- Trustworthiness — We do not hide our formulas and rules, and the dates you enter are never collected or stored.
Calculation rules
Each calculator uses the following rules. These are common conventions, and where helpful we offer options so you can choose the method you prefer.
- Couple days — Day-one-inclusive (start date = day 1) by default, where 100 days = start + 99 days and 1000 days = start + 999 days.
- D-day — The difference in days excluding time. Future D-minus, today D-day, past D-plus.
- Wedding anniversary years — The number of times the same calendar month and day as the wedding date has passed. 25th silver, 50th golden.
A note on accuracy
All results from Anniversary Calculator are based on the date you enter and our published rules, and are for reference. They can differ by about a day depending on whether the first day is included, leap years, and the same-calendar-date rule, and wedding anniversary names can vary by source. Please double-check important dates on a calendar.
Contact
Send suggestions or error reports to jin@zerolabskorea.com. For details on how we handle data, see our Privacy Policy.
Last updated: 2026-06-25