The September 11 attacks occurred on September 11, 2001. To calculate how many years it has been since 9/11 as of May 16, 2025:

• From September 11, 2001, to September 11, 2024, is 23 years.
• From September 11, 2024, to May 16, 2025, is about 8 months.

So, it has been 23 years and about 8 months since 9/11.