Calendar calculators are tools that help users determine specific dates and time intervals. They can calculate the number of days between two dates, find the day of the week for any given date, or convert dates between different calendar systems, such as the Gregorian and lunar calendars. These calculators are useful for planning events, tracking deadlines, or simply satisfying curiosity about dates. Many calendar calculators are available online or as mobile applications, making them easily accessible. Some advanced versions can also account for leap years and holidays, providing more accurate results. Overall, they simplify date-related calculations for everyday use.