Date calculator
How many days between two dates, what date falls n days from one, and how long until a date.
Date arithmetic goes wrong in two places: whether the first day counts, and leap years. This screen gives the gap both ways — the plain difference and the inclusive count — along with the number of weekdays. Leap years follow the Gregorian rule.
Between two dates
What you enter is saved in this browser, so it is still here next time
Left empty, this means today
Left empty, this means today
Between two dates
- Days apart
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- Counting both ends
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- Weeks
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Years, months, days
- Years, months, days
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- Excluding weekends
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The Korean custom for anniversaries — the hundredth day falls 99 days after the first.
Enter a period of at least one year to see the year-by-year table.
Before or after a date
Before or after a date
Left empty, this means today
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Until a date
Left empty, this means today
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Only Saturdays and Sundays are excluded. Korean public holidays move each year, substitute days included, so a fixed list would go stale — none are excluded here.
Make a link with these numbers
Opening the link fills this screen with the same values. Useful for going through it with a partner, or for comparing two sets of conditions.
1 January to 4 September is 246 days, or 247 counting both ends
The gap is the two dates set to midnight and subtracted, so the time of day and the time zone cannot shift it. From 1 January 2026 to 4 September 2026 is 246 days, and counting both days gives 247. Weeks is 246 ÷ 7 rounded to one decimal, 35.1. Years, months and days come to 8 months 3 days — when the day of month falls short, a month is borrowed at the length of the month before the end date, so 31 March to 1 May is exactly 1 month 0 days.
Excluding weekends counts the start date but not the end date
Monday to Friday of the same week is 4 days, not 5. Monday to Thursday are counted and the Friday, being the end date, is not. Friday to the following Monday counts only the Friday, so 1 day. 1 January to 4 September 2026 gives 176. Public holidays are not excluded, so a span containing Lunar New Year or Chuseok comes out higher than the actual working days.
Adding months snaps a missing day to the end of the month
One month after 31 January 2024 is 29 February. Another month on top of that is 29 March, yet two months added at once is 31 March — a date pushed to the end of a month does not spring back, so adding in two steps differs from adding once. Years are added as 12 months, so one year after 29 February 2024 is 28 February 2025. The countdown counts from this browser's date, and any empty field means today.
Common questions
QDoes the hundredth day count the first day?
By Korean custom the day you met is day one, so the hundredth day falls 99 days later. Legal periods work the other way: Article 157 of the Civil Act normally excludes the first day, so the same word points at a different date. Both counts are shown here.
QDo the weekday counts skip public holidays?
No — only Saturdays and Sundays. Korean public holidays shift each year, substitute days included, so a fixed list is guaranteed to go stale. Saying what was excluded seemed better than faking a precision this page does not have.
QHow are months counted?
A month passes when the day-of-month comes round again. One month after 31 January is 28 February (29 in a leap year), since 31 February does not exist — the same rule Article 160 of Korea's Civil Act uses.
QCan I get a date some days before?
Enter a negative amount. −100 days from 4 September 2026 is 27 May. Months and years take negatives too, and a missing day snaps to the end of that month.
QDoes switching the counting rule change the whole milestone table?
Only the day rows — 50, 100, 200, 300, 500, 1,000 and 2,000 — move by one day. The 1st, 2nd, 3rd, 5th and 10th anniversary rows are months added, so they stay: the first anniversary of 1 January 2026 is 1 January 2027 either way.