How this calculator works
This calculator finds the difference between two dates or adds and subtracts time from a date. Enter two dates or a start date and duration to see the result. Use it for event planning, deadline tracking, and date arithmetic. The key inputs are two dates for difference calculation, or a start date and time duration for addition and subtraction. The output is the date difference or the future or past date. Real-world applications include event planning, project management, scheduling, and countdown calculations. The calculator uses JavaScript date arithmetic for day, month, and year differences or additions. Months are added as calendar months, so month lengths and leap years are handled by the browser date object. The difference is calculated between the two selected dates. For event planning, confirm whether your use case counts inclusively. You can subtract days, months, or years from a start date.