Date Calculator

Overview

Calculate D-day countdowns, intervals between two dates, and add or subtract days from a given date. Cover everyday use cases like project deadlines, anniversary D-days, and due date calculations all in one place.

Key Features

• D-day countdown from today to a target date
• Calculate intervals in days, weeks, months, and years between two dates
• Add or subtract N days from a specific date
• Day-of-week display
• Business day calculation excluding holidays

How to Use

1. Select a calculation mode: D-day, date interval, or add/subtract days.
2. Enter dates or pick them from the calendar.
3. Results are calculated and displayed automatically.

Tips

• D-day results can differ by 1 depending on whether the start date is included -- double-check.
• Leap years (February 29) are handled automatically.
• Business day calculations follow Korean public holidays, including substitute holidays.

FAQ

Does the D-day count include the start date?

Typically, D-day counts the remaining days to the target, excluding today. For example, if the target is tomorrow, it shows D-1.

Can it calculate lunar calendar dates?

Currently only the Gregorian (solar) calendar is supported. For lunar date conversion, use a dedicated lunar calendar tool.

Can it handle dates far in the past or future?

It works within the JavaScript Date object range (roughly 271,821 BC to 275,760 AD), which covers any practical use case.