Time difference calculator
How many hours ahead or behind is one city from another — right now and through the year, with daylight saving time and the best hours to call.
Through the year
When daylight saving changes the gap
| Dates | Difference |
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Working day side by side
Popular comparisons
How the time difference is calculated
Each city’s clock is a fixed offset from Coordinated Universal Time (UTC) — for example, Tokyo is always UTC+9 — plus, in many places, an extra hour of daylight saving time in summer. The difference between two cities is simply one offset minus the other, at the same moment.
The catch is the “same moment” part. Because the Northern and Southern Hemispheres have summer at opposite times of year, and because each country picks its own dates, the gap between two cities can take two or even three different values over a year. The “Through the year” table shows exactly when it changes for the pair you picked.
Questions
Why is the difference sometimes an hour off?
Because countries change their clocks on different dates — or not at all. The United States moves its clocks about three weeks before Europe in spring and one week after in autumn, so New York and London are 4 hours apart for part of March and early November instead of the usual 5.
What does “ahead” mean?
A city that is ahead has a later clock time at the same moment. Tokyo is ahead of London: when it is noon in London, it is already evening in Tokyo.
Can the difference be more than 24 hours?
No. The largest gap between inhabited places is 26 hours (from UTC−12 to UTC+14), but between two clocks you only ever see up to one day of difference in the date, plus the hours.