How many days left, how many days since — and how many of them are business days

How to use it

1. Choose a tab at the top: Countdown, Add days or Business days. The Countdown tab opens first with today already set as the "From" date.
2. On the Countdown tab pick a target date. You immediately get the D-number, the weekday, the total span in years, months and days and in weeks, and how many of those days are business days. Give it a name and press Save countdown to keep it in the list below.
3. On the Add days tab type a number of days or tap a chip — 100, 200, 1 year, 1000 or −30 days — to see the resulting date.
4. On the Business days tab switch between Business days between dates and Date after n business days, and use the checkbox to decide whether public holidays are skipped.

How the countdown is counted

The target date itself is D-DAY and the day before is D-1. That is why "100 days" can differ by one depending on whether you count the start date as day 0 or day 1. This day counter treats the start date as day 0 (the day you met is D+0); if you prefer the couple-app convention where the first day is day 1, just subtract one.

Under the big D-30 style label you see the target date with its weekday; if that day is a public holiday its name appears as a badge, and Saturdays and Sundays are marked "weekend". The line below breaks the total down into years, months and days, into weeks and days, and gives the number of business days in the span with weekends and holidays removed. Change the "From" date to count from something other than today, and a target date in the past shows up as D+ with the days elapsed.

Adding and subtracting days

For "what date is 100 days from today?" use the Add days tab. Enter a start date and a number of days and you get the resulting date and weekday, whether it falls on a holiday or weekend, and how far it is from today. A negative number counts backwards, and the 1-year chip adds 365 days. It is handy for 100-day anniversaries, 1000-day milestones or a reminder 30 days before a deadline.

Business day calculator

Business days exclude weekends (Saturday and Sunday) and public holidays — useful for "3 business days" shipping estimates, government processing times and leave planning. In between dates mode the start date is excluded and the end date included, matching the everyday sense of "n days later": Friday to the following Friday is five business days. The result lists how many weekend days and holidays were removed from the calendar span and shows each skipped holiday as a badge with its date and name. In date after n business days mode the calculator walks forward one business day at a time from the start date and reports the arrival date together with the number of calendar days it took; a negative n walks backwards. The holidays applied here are South Korea's:

Saved countdowns

Countdowns are stored only in this browser (up to 20). To see them on another device you will need to add them again there — nothing is kept on a server. The list is sorted by date and each row shows a freshly calculated D-number as of today, so exams, trips and anniversaries can all be watched at a glance. Tap a row to load it back into the calculator, or the ✕ to delete it. If you save without a name, the date is used as the name.

Frequently asked questions

Another app gives me a different "100 days"

It comes down to counting the start date as day 0 or day 1. Here it is day 0, so 100 days after January 1 is April 11 (in a non-leap year); an app that calls the first day "day 1" lands on April 10. If you need that convention, add 99 days instead.

Is the start date counted as a business day?

No. "Three business days from today" starts counting tomorrow, which is the convention used here. The end date is counted, so when both ends are weekdays the result equals the calendar span minus weekends and holidays.

What happens for dates after 2027?

Holiday data covers 2025 to 2027. For other years only weekends are removed, so subtract the holidays yourself for business-day counts beyond 2027. The list is updated each year.

What if I save more than 20 countdowns?

The oldest saved entries are dropped and the most recent 20 remain. Saving the same name and date again replaces the existing entry rather than duplicating it.

Which time zone do the dates use?

Dates are handled as plain calendar days at midnight on your own device, so the D-number changes at your local midnight, not at a server's.

Related tools

• Subscription Cost Calculator — once you know the days to your next renewal, see what that subscription costs you per month and per year
• Percentage, Discount & VAT Calculator — work out what percentage of a countdown has already passed