September 21, 2024 was a Saturday. Below you'll find this date converted across multiple world calendar systems including Hebrew, Islamic, Julian, Chinese, and more.

How do we know the weekday? We use Zeller's congruence — a proven mathematical formula that maps any Gregorian date to its day of the week without lookup tables. 2024 is a leap year (366 days), which shifts weekdays for dates after February 28.

Whether you're planning events, doing historical research, or simply curious about what day of the week a date falls on, this page provides instant answers with verified calendar conversions. All calculations use established astronomical algorithms. Learn about our methodology.