Irish Standard Time (IST)

Irish Standard Time (IST) operates at UTC+1 and is used in the Republic of Ireland during the summer months as part of daylight saving time. It is sometimes referred to simply as "Irish Summer Time" or "Ireland's Daylight Saving Time". During winter, Ireland reverts to Greenwich Mean Time (GMT, UTC+0). In Ireland, "IST" refers to Irish Standard Time, though the same abbreviation is used for India Standard Time globally.

Importance and Global Use of IST

The primary purpose of IST is to extend evening daylight hours during the longer summer months, promoting energy savings, improving public safety, and enhancing opportunities for outdoor activities, commerce, and tourism. This time adjustment benefits sectors like hospitality, retail, transport, and recreation, while aligning daily activities with natural daylight patterns.

Although IST is used only within Ireland, its impact extends internationally, particularly in sectors that coordinate across time zones such as aviation, finance, broadcasting, and digital services. International organizations and businesses working with Ireland must account for IST during the summer to ensure accurate scheduling and communication.

Where and When IST is used worldwide

Other Time Zones in UTC +1

Other time zones share the same offset as Irish Standard Time (IST), but are known by different names. While their clocks align, they may represent different regions or countries based on local time zone definitions.

• British Summer Time – BST
• Central European Time – CET
• West Africa Time – WAT
• Western European Summer Time – WEST