How Daylight Saving Time Affects Time Zones
Clock changes don’t happen everywhere, or on the same day. That’s why the time difference between two cities isn’t always the same.
When clocks change
- United States and Canada (most areas): forward on the second Sunday in March, and back on the first Sunday in November.
- European Union and UK: forward on the last Sunday in March, and back on the last Sunday in October.
- Southern Hemisphere: places such as parts of Australia and New Zealand change at the opposite time of year.
- No change: Japan, China, India and many countries near the equator keep the same time all year.
Why the gap shifts
New York is normally five hours behind London. But the US changes earlier in spring and later in fall, so for a few weeks each year the gap is four hours. Southern Hemisphere changes can shift the gap by two hours across the year.
Avoiding mistakes
- Check meetings booked around clock-change weekends.
- Store times in UTC in software, and convert them when you display them.
- Use city names, such as
Europe/London, instead of fixed offsets.
The Daylight Saving Time Converter checks any date, and the Time Difference Calculator shows today’s gap. Rules can change, and devices rely on updated time zone data.
Tools used in this guide
Daylight Saving Time ConverterConvert a time between cities on any date, with daylight saving handled for you.Time Difference CalculatorFind the time difference between cities and countries.World ClockFree world clock: the current time in any city, day or night, the difference from your time, and a meeting planner that finds working hours that overlap.
Frequently asked questions
Does the clock go forward or back in spring?
Forward by one hour in spring, and back by one hour in fall.
Does UTC change for daylight saving?
No. UTC stays the same all year.
