What this tool does
Calculate D-day countdowns or elapsed days between a target date and a reference date, including D-10, D-Day, and D+3 style results.
Calculate countdowns and elapsed days between dates.
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Calculate D-day countdowns or elapsed days between a target date and a reference date, including D-10, D-Day, and D+3 style results.
Choose a target date and a reference date to calculate whether the result should be shown as a countdown, D-Day, or elapsed D+ value.
Count down to launches, interviews, deadlines, or trips. Measure how many days have passed since an event happened. Check D-day values on today or on a custom reference date.
Count down to launches, interviews, deadlines, or trips.
Measure how many days have passed since an event happened.
Check D-day values on today or on a custom reference date.
Target date: 2026-12-25 Reference date: 2026-12-20
Status: D-5 Days between dates: 5
Yes. If the reference date is after the target date, the calculator shows an elapsed D+ value instead of a countdown.
Yes. You can compare the target date against today or any reference date you choose.
Yes. D-Day Calculator works in the browser so you can enter data, review the result, and copy the output without needing a separate desktop app.
Found a bug, hit a confusing edge case, or want another tool? Send quick feedback about D-Day Calculator.