Free Date Difference Calculator
Find the exact number of days, weeks, months, and years between any two dates — past or future. Perfect for ages, deadlines, anniversaries, and countdowns.
A year has 365 days (or 366 in a leap year). A decade is exactly 3,652 days, and a century is 36,524 days — or 36,525 if it spans 25 leap years.
How it works
How to calculate the days between two dates
Pick your start date
Enter the earlier date — a birthday, contract date, event start, or any past date.
Pick your end date
Enter the later date. It defaults to today, making it easy to calculate age or time elapsed.
Use a quick preset
Not sure where to start? Tap a preset like 'New Year's Day' or '100 days ago' to fill instantly.
Read the breakdown
See the difference in years/months/days, total days, weekdays, weekends, hours, and more.
FAQ
Date difference questions
Everything about calculating the time between dates.
How do I calculate the difference between two dates?+
Subtract the earlier date from the later date. The result is the number of days between them. Our calculator also breaks this down into years, months, days, weeks, hours, and weekdays automatically.
Does the calculator count the start date or end date?+
This calculator counts the days between dates exclusively — meaning neither the start nor end date itself is counted. If you want to include one of the dates (like for age calculations or event durations), add 1 to the total days shown.
How do I calculate someone's exact age?+
Enter the person's birth date as the start date and today as the end date. The result in years, months, and days is their exact age. The calculator automatically uses today's date as the default end date.
What's the difference between calendar days and working days?+
Calendar days count every day including weekends and holidays. Working days (weekdays) exclude Saturdays and Sundays but do not account for public holidays, which vary by country. This calculator shows both.
Can I calculate dates in the future?+
Yes. Set either date in the future and the calculator shows exactly how many days, weeks, months, and years until that date. It's useful for countdowns to events, deadlines, and milestones.
Why do different calculators give different month counts?+
Month differences are ambiguous because months have different lengths (28–31 days). Different tools handle this differently. This calculator uses the most common convention: counting full calendar months, then remaining days — the same method used to calculate someone's age.
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