Date Calculator
What date is 45 days from now? What was the date 3 months before a deadline? Pick a starting date, choose add or subtract, and count in days, weeks, months or years — with an option to count business days only for day-based deadlines.
Results
Formula
How to use this calculator
- Enter the start date.
- Choose add or subtract and the amount.
- Pick the unit — and business-day counting if the deadline is work-based — then Calculate.
Worked example
Add 10 days to November 7, 2026.
- November has 30 days, so no month rollover is needed until the 30th.
- 7 + 10 = November 17.
Result: The result is Tuesday, November 17, 2026.
Frequently asked questions
What happens when adding a month to January 31?
The result clamps into the next month (for example, January 31 + 1 month lands on the last day of February in most calendar libraries). Check the result if your deadline is month-end sensitive.
Do business days include holidays?
No — only weekends are skipped here. For federal-holiday-aware counting, see the Court Date Calculator.
Is the start date counted as day one?
No. Adding 1 day to Monday gives Tuesday — the standard elapsed-time convention that matches most deadline rules.
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