How to Count Your Monthsary: Which Number Are You On?

You know the date. Every 14th, every 9th, every 22nd — that part is easy. The part that trips people up is the number. Is today the 7th monthsary or the 8th? You sit down to write the caption, start counting on your fingers from the month you got together, and somewhere around October you lose confidence.

This guide is only about that: how to count your monthsary so the number is right every time. We will go through which day to count from, a full month-by-month example, a quick formula you can do in your head, and what to do once you pass twelve.

If you are still deciding which day of the month your monthsary should even fall on, or what to do when your date is the 29th, 30th or 31st, we covered those separately in How Does a Monthsary Work in a Relationship and Started Dating on the 31st? When Is Your One Month — both are on this blog. Here we assume you already have your date and just want the number.

Every monthsary count starts from one fixed day, and couples do not always pick the same kind of day. The common choices are:

There is no correct answer, but you do need the same answer. If one of you counts from a first date in January and the other from a yes in February, you will each arrive at a different monthsary number on the same morning. Decide together, once, and that day becomes the zero point for everything that follows.

Whichever day you choose, the day of the month becomes your monthsary date. Start on the 14th and every 14th is a monthsary.

This is where almost every miscount comes from. The day you got together is not your first monthsary. It is day one of the relationship, and the first monthsary only arrives once a full month has passed.

So if you count on your fingers, do not put a finger down for the starting month. Start with the month after it. That one is your 1st monthsary.

Here is a full first year for a couple whose start date is 14 March. Swap in your own day and month and the pattern is identical.

Once you are more than a few months in, counting through a list gets tedious. This is the shortcut:

Months together = (current year − start year) × 12 + (current month − start month). Then, if today’s day of the month is still before your monthsary day, subtract 1, because that month has not completed yet.

Example: you got together on 14 March 2025 and today is 1 October 2026. Year difference is 1, so 1 × 12 = 12. Month difference is October (10) minus March (3) = 7. That gives 19. But today is the 1st and your day is the 14th, so the month is not complete yet: subtract 1. You have been together 18 full months.

That also tells you the next one: on 14 October 2026 you reach 19 months, so the coming date is your 19th monthsary. The number you celebrate is always the number of months that will be complete on that day.

At twelve months the count changes shape, and couples handle it in two ways.

Some keep the running total: the month after the first anniversary is the 13th monthsary, then the 14th, and so on. This is simple, and it is why you see captions like 20th monthsary or 30th monthsary from couples who have been together a couple of years. To get the number, just keep using the formula above — it never resets.

Others switch to years and months: 1 year and 1 month, 1 year and 2 months, and so on, with each new year as an anniversary. To convert, divide the total months by 12. The whole number is the years and the remainder is the months. Eighteen months is 1 year 6 months; thirty months is 2 years 6 months.

Neither is more correct. Whether to keep celebrating monthly after the first year at all is its own question, and we gave it a full post: Do You Still Celebrate Monthsary After an Anniversary?

Months are uneven. February is shorter, some months have 31 days, and the gap between two monthsaries is never quite the same. If you want a number that is exact, count days instead.

Days together is just the number of days between your start date and today. It is harder to do in your head, but it gives you a different set of milestones — 100 days, 365 days, 500 days, 1000 days — that do not line up with the monthsary date at all. Some couples celebrate both. Our How Many Days Have We Been Together calculator post explains how the day count works, including whether to count the first day.

A few patterns cause most of the wrong numbers we see in captions:

The monthsary is celebrated on the date itself, and the number is the months that are complete on that day. If you cannot make the exact date, many couples move the dinner to the nearest weekend but still send the message on the real day. Our post on the best date to celebrate a monthsary goes into how couples handle that.

Some numbers tend to get more attention than others — the 1st, the 6th, the 12th — but that is a habit, not a rule. Any number is worth marking if it means something to you both.

If you would rather not run the formula every month, a CountingUS page does it for you. You enter your start date once, and the page shows how long you have been together in months and days, updating on its own. Add your photos and a message, print or share the QR code, and the next time someone asks which monthsary this is, the answer is one scan away.

Whichever way you count, agree on the start date together, count the first month after it as number one, and the rest follows.