The fast of Tisha B'av 2021 (the Ninth of Av) begins at sundown on July 17, and concludes at nightfall on July 18.

The fast of Tisha b'Av is observed on the Hebrew calendar date of 9 Av (10 Av, when 9 Av is Shabbat). Here are the coinciding secular dates for the upcoming years:

2022:   August 6-7
2023:   July 26-27
2024:   August 12-13
2025:   August 2-3

See Also

When is Rosh Hashanah in 2021, 2022, 2023, 2024, and 2025?
When is Yom Kippur in 2021, 2022, 2023, 2024, and 2025?
When is Sukkot in 2021, 2022, 2023, 2024, and 2025?
When is Shemini Atzeret / Simchat Torah in 2021, 2022, 2023, 2024, and 2025?
When is Chanukah in 2021, 2022, 2023, 2024, and 2025?
When is Purim in 2021, 2022, 2023, 2024 and 2025?
When is Passover in 2021, 2022, 2023, 2024 and 2025?
When is Shavuot in 2021, 2022, 2023, 2024 and 2025?