How Does Daylight Saving Time Affect GMT Time Zone?
GMT itself never changes. GMT (Greenwich Mean Time) is a fixed time standard at UTC+0. However, the UK — which uses GMT in winter — switches to BST (British Summer Time, UTC+1) during DST.GMT vs BST
| Period | UK Time Zone | UTC Offset |
|---|---|---|
| Late Oct - Late Mar | GMT | UTC+0 |
| Late Mar - Late Oct | BST | UTC+1 |
2026 UK DST Dates
- Spring forward: March 29, 2026 (GMT to BST)
- Fall back: October 25, 2026 (BST to GMT)
Impact on Scheduling
When the UK is on BST (UTC+1), the gap with New York (EDT, UTC-4) is 5 hours. When the UK is on GMT (UTC+0) and New York is on EST (UTC-5), the gap is also 5 hours. But during the transition weeks when one has switched and the other hasn't, the gap temporarily becomes 4 or 6 hours.
Why GMT Itself Doesn't Change
GMT is a time standard based on the solar time at the Royal Observatory in Greenwich. It's a reference point, not a time zone that observes DST. UTC is the modern equivalent used for technical purposes.
Quick Answer
GMT never changes. The UK switches from GMT (UTC+0) to BST (UTC+1) on the last Sunday of March, and back on the last Sunday of October.
