Ireland and UK Time: What's the Difference?

Same clock time year-round: GMT in winter, UTC+1 in summer

Stand in Dublin on any date and your watch reads exactly what it reads in London. The two countries share the same offset from UTC every day of the year.

In winter both run on Greenwich Mean Time (GMT, UTC+0). In summer both advance to UTC+1. The Republic of Ireland and the United Kingdom (including Northern Ireland) change their clocks on the same dates, at the same moment, by the same amount. There is never a time difference between them.

The UK calls its winter time GMT and its summer time British Summer Time (BST). Ireland calls its winter time GMT and its summer time Irish Standard Time (IST, UTC+1). Same offset, different label.

Different legal names: BST vs Irish Standard Time

Separate legislation, same clock-change rule.

The UK operates under the Summer Time Act 1972. Ireland uses the Standard Time Act 1968 (as amended). Both laws mandate identical change dates:

• Last Sunday of March, 01:00 UTC, clocks go forward 60 minutes.
• Last Sunday of October, 02:00 local time (01:00 UTC), clocks go back 60 minutes.

The 2026 change dates are Sunday 29 March and Sunday 25 October. The 2027 dates are Sunday 28 March and Sunday 31 October. Both countries follow the same schedule.

Because Ireland calls summer time "standard time," its legal name does not change between seasons. The UK switches from GMT to BST. Ireland stays on "Irish Standard Time" for half the year and "GMT" for the other half.

Why Ireland calls summer time "standard time"

Ireland’s Standard Time Act 1968 made UTC+1 the standard time for the island, with a winter retreat to UTC+0. The intention was to keep the same clock as Northern Ireland and the rest of the UK while asserting a distinct legal identity.

The result is a quirk: in winter, both countries call their time GMT. In summer, the UK calls it BST and Ireland calls it IST. The time on your phone is the same. The label in your calendar may differ.

Northern Ireland: same as the rest of the UK

Northern Ireland is part of the United Kingdom. It uses the Europe/London time zone, exactly like England, Scotland, and Wales. No separate time zone exists for Northern Ireland. Its clocks change on the same dates as the Republic of Ireland because both countries follow the same EU-derived schedule. The difference is legal, not practical.

For a full explanation of the UK’s single time zone, see Does Scotland have a different time zone?.

Common confusion: IST vs India Standard Time vs Israel Standard Time

"Irish Standard Time" shares the abbreviation IST with two other major time zones.

India Standard Time is UTC+5:30. On 15 January 2026, that puts it 5.5 hours ahead of Ireland. On 15 July 2026, it is 4.5 hours ahead.

Israel Standard Time is UTC+2. On 15 January 2026, Israel is 2 hours ahead of Ireland. On 15 July 2026, it is 1 hour ahead.

When you see "IST" in a meeting invitation or a flight schedule, check the context. If the event is in Dublin in July, IST means UTC+1. If it is in New Delhi, IST means UTC+5:30. If it is in Tel Aviv, IST means UTC+2. The abbreviation alone tells you nothing.

Quick-reference table: Ireland vs UK time

Rule of thumb: If you are scheduling a call between London and Dublin, never calculate a time difference. The same rule applies for Belfast, Cardiff, Edinburgh, and Cork. The only thing that changes is what you call the time zone.