Love Confession Day Calculator

Love Confession Day is September 17: start dating then and Christmas is day 100

In South Korea, "Love Confession Day" (고백데이) is September 17. Count the day a couple gets together as day 1, and September 17 to December 25 is exactly 100 days. Someone who confesses on September 17 and hears yes will celebrate their 100th day on Christmas. It is not an official holiday. It spread online, and Korean outlets have written it up around each September 17: the MTN report of 2020 says the date is talked about because a couple who start dating that day reach day 100 on December 25.

The calculator above runs that idea backwards for any date. Pick a target (Christmas Eve, New Year's Day, Valentine's Day, a birthday, a trip) and a milestone (day 100, 200, 1,000, or any number up to 10,000). It tells you which date you would need to start dating, how many days away that is, and, if that date has already passed, what day of the relationship the target would be if you started today. The year clock below the result shades the stretch from your start date to the target and marks every couple day that falls inside it. The list at the bottom counts down to the next couple days in the year, from Valentine's Day to Christmas and New Year's Eve; Korea's own 14th-of-the-month days are available through a filter.

Why count backwards from a date?

• To make a milestone land on a day you already celebrate. Day 100 on Christmas, or day 100 on New Year's Day, means one celebration instead of two competing ones. That pairing is the whole reason Love Confession Day caught on.
• To find a new plan after Love Confession Day has passed. If September 17 is behind you, change the target. In a non-leap year, starting on September 24 puts day 100 on New Year's Day, November 7 puts it on Valentine's Day, and December 5 puts it on March 14. MTN's 2020 report adds that, because many couples treat day 100 as more precious than any other anniversary, people who missed Valentine's Day, White Day or Rose Day use Love Confession Day to confess. The same logic works for any other date.
• To see what day of the relationship an event will be. Already seeing someone, or about to? Enter the target and the calculator shows which day it would be if you began today.
• To plan around a date that cannot move. A wedding, a graduation, a flight home: type any date into the target field and the result follows. If you are already together and want to count forward from your first day, the couple anniversary calculator is the better fit.

How the calculation works

1. Start date = target date minus (N − 1) days. Korean couples commonly count the day they get together as day 1, so day 100 sits 99 days after the start. December 25 minus 99 days is September 17.
2. Check it by hand. September 17 to 30 is 14 days, October has 31, November has 30, and December 1 to 25 is 25. That adds up to 14 + 31 + 30 + 25 = 100, with September 17 as day 1 and December 25 as day 100.
3. Counting from zero instead. Some people call the next day day 1, so the start day is day 0. Then you subtract the full 100 days, and the date for Christmas moves to September 16. Switch off "Count the first day as day 1" to use this version. The two methods always differ by exactly one day, so agree with your partner which one you use.
4. Leap years. If February 29 falls between the start and the target, one extra day is in the count. Day 100 on a March 14 target starts on December 5 of the year before in a normal year, but on December 6, 2027 for March 14, 2028. The calculator uses the real calendar, so it adjusts without any input from you.
5. What happens when you tap a target day. The calculator picks the nearest year in which your start date is today or later. In October, tapping Christmas shows next year's Christmas and next year's September 17, because this year's has gone.

Start dates for popular targets

These are for a target in a non-leap year. If February 29 falls inside the stretch, the start date is one day later (for March 14, 2028, day 100 starts on December 6, 2027). The weekday of the start date changes every year, so check it in the calculator.

Couple days in the year

The countdown list and the year clock show the days that matter in English-speaking countries, plus Love Confession Day itself. Korea's own couple days (the monthly 14th days and Pepero Day) are hidden until you choose the "Korea's 14th days" filter; they are explained in the next section. Several are informal observances, and none obliges you to do anything.

Example: start on September 24, 2026, and National Boyfriend Day (October 3) is day 10, Christmas Eve is day 92, Christmas is day 93, New Year's Eve is day 99 and New Year's Day is day 100. The calculator lists every couple day inside your own stretch, with its day number.

Korea's own days: the monthly 14th and Pepero Day

Korea has a custom of naming the 14th of nearly every month after a couples' theme. The Korea Herald, in a piece on the monthly 14th days, notes that the origins of many are unclear, that the 14th probably became significant because of Valentine's Day, and that the habit of inventing new days started when March 14 was designated White Day. The meanings below come from that article, so treat them as how the days are commonly described, not as rules. None of them is an official holiday.

For a couple who start on September 17, Wine Day is day 28, Pepero Day is day 56, Movie Day is day 59 and Hug Day is day 89. To see them in the list and on the clock, switch the filter to "Korea's 14th days".

Where these days came from

• White Day. The page of Japan's national candy and confectionery association says its members decided in June 1978 that March 14 would be "Candy Day", and that the first White Day event was held in March 1980. The Korea Herald says the day's origin is uncertain and that some believe it came from Japan.
• Love Confession Day. Kukmin Ilbo (2019) describes it as a custom that began a few years earlier: a couple who get together on September 17 reach day 100 on Christmas. The article adds that, unlike Valentine's Day and White Day, there is no set gift, which some online commenters liked because it avoids the marketing.
• International Kissing Day. Wikipedia says it originated in the United Kingdom and was adopted worldwide in the early 2000s, and names no founder; it describes the idea as kissing for kissing's sake. Treat it as an informal observance.
• National Boyfriend Day. Wikipedia calls it an unofficial event on October 3, mainly from the United States and driven by social media, thought to have originated around 2014. It names no founder.
• The monthly 14th days. The Korea Herald says their origins are unclear.

Common mistakes

• Subtracting 100 when you mean day 100. If the start day counts as day 1, you subtract 99, which is why Love Confession Day is September 17 and not September 16.
• Waiting for a date that has gone. If you search in October, this year's Love Confession Day has passed. Use the "if you start today" rows, or aim at next year's.
• Assuming Pepero Day is a 14th. It is November 11. November 14 is Movie Day.
• Forgetting leap years. The extra February 29 shifts the start date by a day when it falls in the stretch. Counting by hand is where this usually goes wrong.

Limits

• Love Confession Day and the 14th days are informal. Names and meanings vary by source, and whether to mark any of them is up to the two of you.
• The tool only does date arithmetic. It cannot tell you whether the other person feels the same way, so choose a moment that suits them over a date that suits the calendar.
• "Today" is your device's date. A different time zone setting can move a result by one day.
• It counts up to day 10,000, and the target must be today or later.
• Everything is calculated in your browser, and nothing you enter is sent to a server.

Sources

• 01MTN: report on Love Confession Day (Korean)Says Sept 17 is Love Confession Day because a couple who start dating then reach day 100 on Dec 25 (Christmas), 2020-09-17. Checked 2026-10-11.
• 02Kukmin Ilbo: Love Confession Day article (Korean)Sept 17 start puts day 100 on Christmas; custom began a few years before 2019; no set gift. Checked 2026-10-11.
• 03The Korea Herald: Every month's 14th is a special day for KoreansMonthly 14th days, Pepero Day, White Day. Checked 2026-10-11.
• 04Wikipedia: International Kissing DayJuly 6; began in the United Kingdom, adopted worldwide in the early 2000s; no named founder. Checked 2026-10-12.
• 05Wikipedia: National Boyfriend DayOctober 3; unofficial, social-media holiday; thought to date from around 2014. Checked 2026-10-12.
• 06All Japan Candy Association: the story of White Day (Japanese)March 14 decided as Candy Day in June 1978; first White Day event in March 1980. Checked 2026-10-11.

Frequently asked questions

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