A birthday calculator is a tool that helps individuals determine the day of the week they were born, how many days until their next birthday, or even how many days they have lived. It can also provide information about zodiac signs and birthstones associated with specific dates. These calculators are often available online or as mobile applications, making them easily accessible. Users simply input their birth date, and the calculator quickly generates the desired information. This can be a fun way to celebrate one's birthday or learn more about personal astrological traits related to their birth date.