Calculate days between dates, countdown timers, age, and time durations.
Use this category when you need calendar-correct day counts, age in multiple units, or elapsed time — not mental arithmetic. D-Day and date-difference tools answer different questions (countdown to one target vs. span between two dates); mixing them up is a common mistake. Age tools may apply regional age-counting customs on dedicated pages: always note which convention is used. Results are deterministic from the dates you enter; they do not account for business calendars, holidays, or contract clauses unless stated on the tool.
Each tool below has a different purpose, assumptions, and common pitfalls. Read the framing first — the same numbers can mean very different things depending on the formula.
Find your exact age in years, months, and days — accurate to the day. Enter your date of birth and optionally choose a custom "as of" date to calculate age at any point in time, past or future. Leap years are handled automatically. Includes Korean man-nai (만 나이) for Korean administrative contexts.
The D-Day Calculator counts exactly how many days remain until a future event — or how many days have passed since a past date. The name comes from military usage where "D" marks a designated target date, but in everyday use it is most commonly used for personal and professional countdowns: exam dates, travel departures, product launches, anniversaries, visa expiry dates, payment due dates, and project deadlines. Unlike the Date Difference Calculator (which compares two arbitrary dates you specify), a D-Day calculator is oriented around today — it automatically answers "how many days until or since [event]?" You can also set a custom start date if you need to count from a date other than today.
The Date Difference Calculator answers one deceptively simple question: exactly how far apart are two dates? Enter a start date and an end date to get the precise gap in days, weeks, months, and years. This is most useful when the exact count matters — for project deadlines where contract language specifies "30 calendar days," for lease expiry calculations where one day off has legal consequences, for loan term verification, for checking how long until a visa or passport expires, or for confirming probationary periods and notice periods at work. The month count uses actual calendar months, not 30-day approximations — so the gap from January 1 to March 1 is exactly 2 months regardless of how many days are in January and February. A business days option (excluding weekends) is available for work-related calculations.
The Time Duration Calculator finds the exact duration between any two times of day — down to the second. Enter a start time and end time to get the elapsed time in hours, minutes, and seconds. You can also add a duration to a start time to find the end time, or sum multiple time intervals together for total time tracking. The calculator handles overnight durations (crossing midnight) automatically. Ideal for tracking work sessions, timing events, calculating billing increments, cooking timers, and travel time planning.
Use our Date Difference Calculator — enter a start date and end date to instantly see the total days, weeks, and months between them.
Yes. The Age Calculator shows your age in years, months, and days, plus the total number of days since your birth.
Enter a target date and the calculator counts down (or up) the exact number of days remaining until (or since) that date.
All our date calculators account for leap years, varying month lengths, and daylight-saving transitions automatically.