How Mardi Gras Date Is Determined

Mardi Gras (Fat Tuesday) falls on the Tuesday before Ash Wednesday—the start of Lent in the Western Christian calendar.

The Calculation Chain

1. Easter Sunday = First Sunday after the first full moon on or after the vernal equinox (fixed as March 21 for calculation).
2. Ash Wednesday = 46 days before Easter Sunday (40 days of Lent + 6 Sundays).
3. Mardi Gras = Day before Ash Wednesday = 47 days before Easter.

Date Range

Because Easter varies (March 22 – April 25), Mardi Gras falls between February 3 and March 9.

Examples

• 2024: Easter Mar 31 → Mardi Gras Feb 13
• 2025: Easter Apr 20 → Mardi Gras Mar 4
• 2026: Easter Apr 5 → Mardi Gras Feb 17
• 2027: Easter Mar 28 → Mardi Gras Feb 9

Key Points

• Always a Tuesday.
• Always in February or March.
• Determined by lunar cycle (via Easter), not fixed calendar.
• Carnival season begins Jan 6 (Epiphany); Mardi Gras is the climax.

So the date isn't "chosen"—it's calculated from the ecclesiastical moon.