Time difference calculator
The difference between two places is not a fixed property of the pair — it depends on the date, and for a lot of pairs it changes twice a year.
The short answer
Subtract the two UTC offsets — on the date you care about. Berlin at UTC+2 and New York at UTC−4 differ by six hours in summer.
The date qualifier matters: many pairs have a different answer in winter than in summer.
Common differences
| Pair | Winter | Summer | Stable? |
|---|---|---|---|
| Los Angeles → New York | 3 hours ahead | 3 hours ahead | Yes |
| Chicago → New York | 1 hour ahead | 1 hour ahead | Yes |
| New York → London | 5 hours ahead | 5 hours ahead | Mostly* |
| New York → Mumbai | 10:30 hours ahead | 9:30 hours ahead | No |
| London → Mumbai | 5:30 hours ahead | 4:30 hours ahead | No |
| London → Sydney | 11 hours ahead | 9 hours ahead | No |
| Berlin → Singapore | 7 hours ahead | 6 hours ahead | No |
| Phoenix → New York | 2 hours ahead | 3 hours ahead | No |
*New York → London is five hours for most of the year, but drops to four for about three weeks each spring and a week each autumn, when the two regions have not yet both switched.
When a gap is stable, and when it is not
Stable when both sides change their clocks on the same dates — which in practice means both are in the same country or the same regulatory bloc. All the US-internal pairs are stable. All the intra-EU pairs are stable.
Not stable when one side observes daylight saving and the other does not (New York ↔ Mumbai; Phoenix ↔ anywhere), or when both do but on different dates (New York ↔ London), or when they are in opposite hemispheres (London ↔ Sydney, where the gap swings by two hours across the year).
The southern hemisphere case
London to Sydney is the widest swing here: 11 hours ahead in the northern winter and 9 hours ahead in the northern summer.
Both places observe daylight saving, but in opposite seasons — so there are periods when one is springing forward while the other is falling back, and the gap moves by two hours over the year rather than one.
Difference versus overlap
A time difference tells you how far apart two clocks are. It does not tell you when you can both be awake — that depends on the difference and on each side's waking hours.
An eight-hour difference and a nine-hour difference sound similar and are not: one leaves a usable window and the other leaves none. See time zone overlap.
Related: Time zone calculator · When are two cities both awake?
Timezone: World Clock Widget
A world clock, converter and live day/night map for iPhone — 325 cities, offline, no account.
Figures on this page are computed from the IANA time zone database. Last generated 2026-08-18.