If I arrive in Thailand on June 30, when is my 30-day visa valid until?

The arrival date of June 30 is counted as day 1 for a 30-day visa exemption in Thailand. Therefore, your visa would be valid for 30 days and would end on July 29. However, opinions vary in the comments regarding whether the arrival day should be counted and when the exact exit date is. Most agree that departing on July 30 would not be allowed under a 30-day visa as it effectively counts only 29 nights.