Date Calculator : Add or Subtract Days, Weeks, Months, & Years
Quickly calculate target deadlines, maturity dates, and milestones by adding or subtracting units of time from any given starting date.
Interactive Calculator
100% Client-Side EngineTarget Result Date
Oct 19, 2026
Monday • 2026-10-19
Step-by-Step Examples
Adding 90 Days to a Contract Start
Adding 90 days to January 15, 2024.
Inputs: Start Date: 2024-01-15, Add: 90 Days
Result: Sunday, April 14, 2024
Properly accounts for 29 days in Feb 2024 and 31 in March.
How to Use This Tool
- Choose your starting date.
- Select whether to Add or Subtract time.
- Enter years, months, weeks, or days.
- Click Calculate to see the resulting date and day of the week.
Frequently Asked Questions
If adding 1 month to January 31, the calculator adjusts to the last valid day of February (Feb 28 or Feb 29).
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