Monthsary Calculator: How to Count Months in a Relationship

It sounds like a math problem, but it actually trips up a surprising number of couples: how do you count months in a relationship? If you started dating on the 15th, is your "one month" exactly 30 days later, or is it the 15th of next month? Do you count the month you started? What about partial months? Here's the simple version of how couples actually count it.

The Short Answer

Count from the calendar day you started dating, not from a "30-day chunk." If you started on June 15th, your one-month anniversary is July 15th. Two months is August 15th. And so on. This is the way most couples track months and anniversaries, and it's how every anniversary calculator (including ours) does it.

How to Count Months in a Relationship — Step by Step

1. Pick your start date. The day you officially started dating, or the day you both agreed you were a couple. If it's fuzzy, pick the date that feels most meaningful to both of you.
2. Add one calendar month at a time. Same day, next month. June 15 → July 15 → August 15.
3. Skip the math for partial months. If today is June 25 and you started on June 15, you're "10 days into your first month" — not 0.33 of a month. People don't talk in fractions of months.
4. Handle short months gracefully. If you started on January 31, your one-month is February 28 or 29 (the last day of Feb), not "March 3." Calendar months win.

Do You Count the Month You Started Dating?

No. The day you started dating is "day one of month one." You don't count it as a completed month until you reach the same calendar day the following month. So if you started on June 15, you finish your first month on July 15 — that's when you say "we've been together one month."

How Do You Count Anniversary Months?

Same way. Your "monthly anniversary" (sometimes called a "monthsary" by long-distance couples especially) is the same calendar day each month as your start date. Many couples celebrate the smaller monthly milestones in the first year, then shift to yearly anniversaries after that.

How to Know Your Monthsary Date

Your monthsary date is the same calendar day each month as the day you started dating. If you got together on March 8th, every 8th of the month is a monthsary. April 8th is your 1-month monthsary, May 8th is your 2-month, and so on. You don't recalculate it — it's locked to that calendar day forever.

If you genuinely can't remember the day, pick the date that feels closest and agree on it together. Most couples treat this as a soft commitment, not a legal one. The point is to have something to celebrate.

How to Calculate Your Monthsary Date

The math is simple: start date day-of-month → same day next month = 1-month monthsary. No need to count 30 days. No need to convert weeks. Calendar days only.

• Started dating February 14 → monthsaries on March 14, April 14, May 14…
• Started dating October 22 → monthsaries on November 22, December 22, January 22…
• Started dating July 5 → monthsaries on August 5, September 5, October 5…

If you'd rather skip the manual math, our free anniversary calculator figures it out instantly — just enter your start date and you'll see every upcoming monthsary, the days remaining, and the milestones worth celebrating. Inside the OurCouple app, your monthsary gets tracked automatically and both partners get a reminder before each one.

Monthsary vs Anniversary: What's the Difference?

A monthsary celebrates the same calendar day each month. An anniversary celebrates the same calendar day each year. Both share the same start date — the day you began your relationship.

Most couples celebrate monthsaries during the first year (when every month feels like a milestone), then shift to anniversaries from year one onward. Some keep both going forever — there's no rule. The word "monthsary" is especially popular in the Philippines, India, Korea, and across Southeast Asia, where monthly relationship milestones are widely celebrated.

How to Count Your Monthsary if You Started Dating on the 31st

Edge case that trips up a lot of couples: what if your start date doesn't exist in the next month? If you started dating on January 31st, February only has 28 (or 29) days. There is no February 31st.

The convention couples use: celebrate on the last day of the shorter month. So January 31 → first monthsary is February 28 (or 29 in leap years). The following month, you return to the 31st (March 31, May 31, etc.) — only the short-month monthsary shifts. Same logic applies if you started on the 29th or 30th.

Common Milestones Couples Track

• 1 month, 3 months, 6 months — the early months feel huge.
• 100 days — popular in Korea, Japan, and increasingly worldwide.
• 1 year — the first big one.
• 500 days, 520 days — 520 sounds like "I love you" in Mandarin (wǒ ài nǐ).
• 1000 days — a quiet but meaningful one.
• Every yearly anniversary after that.

Want the full list of milestones — including the random ones nobody told you about? Check our guide to relationship milestones.

The Lazy Way: Just Use a Calculator

If you'd rather not count manually, our free anniversary calculator does it for you — total days, weeks, months, years, and every upcoming milestone. Free, instant, no signup. And inside the OurCouple app, your anniversaries get tracked automatically and remind you both before each one — so you never miss a 100-day or a 1000-day again.

Quick Recap

• Count by calendar day, not 30-day blocks.
• Same day, next month = 1 month.
• Don't count the day you started as "month one complete."
• For short months (Feb), use the last day of the month.

That's it. Now go celebrate the next one.