Anniversary Calculator — Days Together & Milestones
Enter a start date, such as your first date, wedding day or the day a business opened, and see how many days it has been plus upcoming milestones like 100 days, 200 days and your 1st anniversary in one go.
Upcoming milestones
💡 Bookmark this page (Ctrl+D, or Cmd+D on a Mac) and it recounts from today every time you open it, so your day count and next milestone stay up to date.
How to use
How the anniversary calculator works
This anniversary calculator turns a single date into a full calendar of milestones. Enter the day something began, such as your first date, your wedding day, the day a business opened or the day a pet came home, and press the button. You get today’s day count, the date of your next milestone and a list of the next ten, each with the number of days left. It is built for couples, but it works just as well for a work anniversary, a move-in date or the opening day of a shop. An optional name or note, such as “Our first date” or “Shop opening,” labels the result and the picture you can save.
Is the start date day 1 or day 0?
This is the one rule worth knowing, because it decides which calendar date a milestone lands on. This calculator counts the start date itself as day 1. The next day is day 2, and so on. That means your 100th day falls 99 days after the start date, not 100. Many people count from day 0 instead, so their “100 days” lands one day later. Neither way is wrong. If you prefer day 0, simply celebrate the day after the date shown for any milestone counted in days. Yearly anniversaries are not affected, because they follow the calendar.
Milestone date = start date + (N − 1) days
Day count today = (today − start date) + 1
A worked example
Say your start date is Saturday, February 14, 2026. Counting that day as day 1, the milestones fall on these dates.
| Milestone | How it is counted | Date |
|---|---|---|
| 100 days | Start date + 99 days | May 24, 2026 |
| 200 days | Start date + 199 days | September 1, 2026 |
| 300 days | Start date + 299 days | December 10, 2026 |
| 1st anniversary | Same month and day, 1 year later | February 14, 2027 |
| 500 days | Start date + 499 days | June 28, 2027 |
| 1,000 days | Start date + 999 days | November 9, 2028 |
With the start date counted as day 0, every day-based date above moves one day later (100 days would be May 25, 2026). The 1st anniversary stays on February 14, 2027.
Day milestones versus yearly anniversaries
The tool builds two lists and merges them by date. The first is every 100 days: 100, 200, 300 and so on, up to 20,000 days. The second is the yearly anniversary, from the 1st to the 30th. A yearly anniversary is the same month and day, one year later. That is 365 days after the start date, or 366 when a leap day falls in between. With the start date as day 1, your 1st anniversary is therefore day 366 (or day 367), so it never lines up with a 100-day mark. If a day milestone and an anniversary fall on the same date, both are shown. If your start date is February 29, the yearly anniversary appears on March 1 in years that have no leap day.
What the result shows
- The big number. How many days it has been, counting the start date as day 1. If the start date is still ahead, the number counts down to it instead.
- Start date and next milestone. The start date with its weekday, and the nearest milestone with how many days remain.
- Upcoming milestones. The next ten, nearest first, each with its date, weekday and days left. The nearest one is outlined, and a banner appears on the day you hit a milestone.
A note on the 100-day tradition
Celebrating 100 days together is a well-known custom in Korea, where couples often keep going with 200, 300 and 1,000 days. The habit is commonly linked to baegil, the traditional celebration of a baby’s 100th day. Counting the start date as day 1 is the everyday convention there, which is why this tool works that way. Elsewhere, couples more often mark months and years, but a round number like 100 days or 1,000 days (roughly 2 years and 9 months) can be a fun excuse for a small celebration between the big dates.
Traditional wedding anniversary themes
If you are counting a marriage, the yearly anniversaries come with a long-standing tradition of themes. The list below shows the commonly cited traditional themes for a few years. Lists vary slightly by country and source, and many sources also publish a separate modern list, so treat these as inspiration rather than rules.
| Year | Traditional theme | Year | Traditional theme |
|---|---|---|---|
| 1st | Paper | 15th | Crystal |
| 2nd | Cotton | 20th | China |
| 3rd | Leather | 25th | Silver |
| 5th | Wood | 30th | Pearl |
| 10th | Tin or aluminum | 40th | Ruby |
| 50th | Gold | 60th | Diamond |
What else you can count
- Dating and marriage. First date, engagement or wedding day.
- A business. The day you opened, launched or signed the lease.
- A pet. The day you adopted a dog or cat, which makes a sweet 100-day or 1-year card.
- A home. Move-in day, or the day you closed on a house.
- A job or a habit. Your first day at work, or the day you started a new routine.
Saving, sharing and privacy
The calculator remembers the last name and start date you entered, so reopening or bookmarking the page recounts everything from today. Press Copy link to get a web address that contains the name and start date in plain text, which means anyone you send it to can read them. When they open it, the days are counted from their own today. Save as image draws a picture with the name, the day count, the start date and the next four milestones. All of this happens in your browser, and nothing is uploaded. The saved entry stays in this browser only and will not appear on your other devices.
Tips for using your milestones
Put the next milestone in your phone’s calendar as soon as you see it, because round-number days sneak up quickly. Remember that the count uses the date on your device, so it rolls over at your local midnight, and if you travel across time zones it follows the clock you are on. When you share a result with someone who counts from day 0, tell them which convention you used. Finally, you do not need a big plan. A handwritten note, a favorite meal or a short walk back to the place you first met is often enough.
Frequently asked questions
Does the anniversary calculator count the start date as day 1 or day 0?
Day 1. The start date is day 1, so the 100-day milestone is the start date plus 99 days. If you count from day 0, add one day to each milestone counted in days. Yearly anniversaries do not change.
How do I find my 100-day anniversary date?
Enter your start date and press the button. The 100-day date appears in the milestone list if it is still ahead. To check it by hand, add 99 days to the start date. For a start date of February 14, 2026, that gives May 24, 2026.
Is the 1st anniversary the same as 365 days?
No. The 1st anniversary is the same month and day one year later, which is 365 days after the start date, or 366 across a leap day. With the start date counted as day 1, that is day 366 or 367, so the tool lists it separately from the milestones counted every 100 days.
Can I use it for a wedding, a business or a pet?
Yes. The calculator only needs a start date, so it works for a wedding day, a shop opening, an adoption day or any other starting point. The result is labeled with whatever name you type.
How many milestones does it show?
It shows the next ten, nearest first. Behind the scenes it covers every 100 days up to 20,000 days and yearly anniversaries from the 1st to the 30th, and it picks the ten that are still ahead.
What happens if my start date is in the future?
The big number counts down the days until your start date, and the milestone list shows the dates that will follow it. That is handy for planning a wedding, a launch or a move.
Is my information private?
Yes. Everything is calculated in your browser. The last name and start date are remembered only in this browser, and a copied link contains what you typed, so share it only with people you want to see it.