Date Calculator
Calculate the difference between dates, add or subtract time periods, and explore date details.
Find the Duration Between Two Dates
Select two dates to see the difference
Add or Subtract Time from a Date
Select a date and time period to calculate
Explore Date Details
Select a date to see its details
About Date Calculator
This free date calculator helps you perform a variety of date-related calculations quickly and accurately. Whether you need to find the exact number of days between two dates, add or subtract time periods from a date, or explore details about a specific date, this tool handles it all directly in your browser with no data ever leaving your device.
The "Days Between Dates" mode calculates the precise duration between any two dates, showing results in multiple formats: total days, weeks and days, months and days, and years, months, and days. It also separates business days (weekdays) from weekend days, which is essential for project planning, contract deadlines, and HR calculations. The distinction between calendar days and business days matters in many professional and legal contexts, since contracts and deadlines often specify "business days" rather than calendar days.
The "Add/Subtract" mode lets you calculate a future or past date by adding or subtracting a specific number of days, weeks, months, or years from any starting date. This is useful for calculating due dates, warranty expirations, subscription renewals, or any scenario where you need to project a date forward or backward in time. The "What Day Is It?" mode provides comprehensive information about any date, including the day of the week, day of the year, ISO week number, quarter, and leap year status.
All calculations use your browser's native Date API and handle edge cases like leap years, varying month lengths, and year boundaries correctly. No external libraries are required, and no data is sent to any server.
FAQ
Q: How are business days calculated?
A: Business days count only weekdays (Monday through Friday), excluding Saturdays and Sundays. Note that this calculator does not account for public holidays, as those vary by country and region. For precise business-day calculations involving holidays, you may need to manually adjust the result.
Q: Does the calculator handle leap years correctly?
A: Yes. The calculator correctly accounts for leap years when computing date differences and when adding or subtracting time periods. February 29 is properly handled in all modes.
Q: What is an ISO week number?
A: The ISO week number follows the ISO 8601 standard, where weeks start on Monday and the first week of the year is the one containing the first Thursday. This means some dates at the start or end of a year may belong to the previous or next year's week numbering.
Q: Is my data stored or sent anywhere?
A: No. All calculations happen entirely in your browser using JavaScript. No dates or results are transmitted to any server or stored anywhere.