Add or subtract time from dates, and calculate the difference between two dates
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This date calculator provides two powerful functions:
Choose a starting date and add or subtract any combination of years, months, weeks, and days. The calculator automatically handles:
Select two dates to calculate the exact difference between them in years, months, weeks, days, hours, and minutes. Perfect for project planning, countdowns, and tracking time periods.
Calculate project deadlines by adding weeks or months to start dates, or find how much time remains until completion.
Find the exact date for events scheduled months in advance, or count down days until important occasions.
Calculate payment due dates, contract expiration dates, or billing cycles with precision.
Determine exact vacation lengths or find optimal travel dates by adding days to your preferred start date.
The calculator automatically accounts for leap years (February 29) when adding or subtracting time. It uses JavaScript's native Date object which correctly implements leap year rules.
When adding months results in an invalid date (like Feb 31), the calculator automatically adjusts to the last valid day of that month (Feb 28 or 29). For example, Jan 31 + 1 month = Feb 28/29.
Yes! You can either use the "Subtract Time" option, or simply enter a past date in the "From Date" field when calculating date differences. The calculator works with any valid date.
Both weeks and days can be used interchangeably (1 week = 7 days). The separate fields are provided for convenience - use whatever unit makes most sense for your calculation.
This calculator works with calendar days. It counts every day including weekends and holidays. For business day calculations, you'll need to manually exclude weekends and holidays.
If a project starts on March 1, 2026 and takes 3 months and 2 weeks to complete, the deadline would be June 15, 2026.
Someone born on January 1, 2000 would be approximately 9,533 days old as of February 6, 2026.
A 2-year contract signed on June 15, 2024 would expire on June 15, 2026 (730 days later).
From conception date, adding 40 weeks (280 days) gives the estimated due date.
This date calculator was created by the ToolsVault team to provide accurate date arithmetic and calculations. The tool handles complex calendar rules including leap years, varying month lengths, and time zone considerations.
Created by: ToolsVault Calculator Tools Team
Accuracy: Accounts for leap years and calendar edge cases
Last updated: February 6, 2026
Next review: May 2026