Calculator
Date Calculator
Calculate differences between dates or add/subtract days from any date.
Where date math shows up in real work
You might need the number of days between contract dates, the due date after a 30-day policy, or the weekday of a past release. Manual counting across months is where mistakes happen, especially with leap years and different month lengths.
Use the tool
How to avoid wrong answers
Confirm whether the business rule is inclusive of both start and end dates, because tools differ. If you are doing legal date math, a jurisdiction’s definition of a “business day” can matter, and that is not a universal default. If you are scheduling globally, be careful about time zones; this tool focuses on calendar dates, not the full 24-hour global timeline.
Not legal advice
Use this to assist arithmetic; verify time-sensitive rights and deadlines with the governing authority or counsel.