D-Day Calculator
About this Tool
Track days until or since important dates with D-n, D-DAY, and D+n labels, live second-by-second countdowns, couple milestone tables (100 days, 1 year), and resignation actual workdays. AllThatConverter provides 3 dedicated calculator tabs: ① General & Countdown with quick presets for exams, Christmas, and New Year, ② Couple & Anniversary table listing 100-day intervals and yearly anniversaries, and ③ Resignation & Workdays calculating actual business days remaining (excluding weekends). Saved countdowns stay private in this browser only without sending personal milestones to a server.
Processed safely on your device
Everything happens in your browser on this device. Your files are never sent to our servers—so you can use it with peace of mind.
How to Use
Choose your mode from the top tabs: General & Countdown, Couple & Milestones, or Resignation & Workdays.
In General mode, select a quick preset (such as CSAT exam or Christmas) or enter a custom date, and toggle live countdown to see remaining hours, minutes, and seconds.
In Couple mode, input the anniversary start date to see day counts and an automatically generated table of 100-day milestones and yearly anniversaries with days remaining.
In Resignation mode, specify your last working day and schedule (5-day or 6-day week) to calculate exact working days left before your resignation.
Click the copy button to copy clean, formatted milestone tables or D-day results directly to your clipboard.
Key Scenarios & Use Cases
Exam, CSAT, and Certification Countdowns
Check remaining days and live second-by-second countdowns for major exams and tests to manage study schedules effectively.
Couple 100-Day and Yearly Anniversaries
View an instant milestone table showing 100th, 200th, 300th, and 1-year dates along with weekdays and countdown badges.
Resignation and Notice Period Workdays
Calculate exact actual office working days left before resignation or project launch, filtering out weekends and rest days.
Streak and Habit Days Since Milestone
Track sobriety, fitness streaks, or days since quitting smoking with D+n elapsed day counts.
Personal Planning Without Cloud Sync
Keep private countdowns on-device when you do not want calendar cloud sharing.
Frequently Asked Questions (FAQ)
It switches to milestone counting where the start date is counted as day 1 (D+1). For example, day 100 is start date + 99 days, matching standard East Asian couple anniversary customs.
Based on your chosen workweek (5-day workweek excludes Saturdays and Sundays; 6-day excludes Sundays), it counts only the business days you actually need to report to work.
Only in this browser’s local storage. They are never sent to a server; clearing browser data deletes them.
Yes. Simply click the 'Copy all milestones' button above the table to copy a cleanly formatted list ready to paste into messaging apps or notes.
Counts use local calendar dates in your browser. For timezone-critical events, set the civil date you intend to celebrate.