Ireland uses Irish Standard Time (IST) during the summer months, which is UTC+1. In the winter months, Ireland follows Greenwich Mean Time (GMT), which is UTC+0.

Ireland observes Daylight Saving Time. During this period, the time zone shifts from GMT (UTC+0) to Irish Standard Time (IST), which is UTC+1.

The time difference between Ireland and the United States varies by U.S. time zone. For example, Ireland is 5 hours ahead of Eastern Standard Time (EST) and 8 hours ahead of Pacific Standard Time (PST) during the winter.

During the winter, Ireland shares the same time zone as the UK (GMT, UTC+0). During the summer, Ireland is in the same time zone as Western Europe, which is Central European Summer Time (CEST, UTC+2).