Enter the time in the origin zone, the standard time offset of the origin zone from UTC, and whether daylight saving is in effect there, and the same for the destination. Offsets are in minutes relative to UTC, so minus 300 is UTC minus five hours, the Eastern Standard Time offset. Look up the current offset and whether daylight time applies on that date, since the dates of changes differ by country and some places do not observe daylight saving at all.
Time Zone: worked example
| Time in the origin zone | 12:00 PM |
|---|---|
| From zone (standard time) | US Eastern (UTC−5) |
| Daylight saving in the origin zone | No |
| To zone (standard time) | UTC or London (UTC+0) |
| Daylight saving in the destination zone | No |
| Time at the destination | 5:00 PM |
| Day shift (−1, 0 or +1) | 0 |
| Hours ahead of the origin | 5 |
Daylight saving rules change and differ across countries, and the start and end dates are not the same in the United States, Europe and elsewhere, so an offset that is right in one week can be wrong in the next. Some zones use half-hour or 45-minute offsets. Historical dates may follow different rules.
Use a calendar app that stores time zones for important events.
Time Zone: formula
Common error: Assuming the difference is the same all year. It changes twice a year, and some regions do not observe daylight saving at all.
Time Zone: changing Time in the origin zone
| Time in the origin zone | Time at the destination | Day shift (−1, 0 or +1) | Hours ahead of the origin |
|---|---|---|---|
| 11:00 AM | 4:00 PM | 0 | 5 |
| 11:30 AM | 4:30 PM | 0 | 5 |
| 12:00 PM (example) | 5:00 PM | 0 | 5 |
| 12:30 PM | 5:30 PM | 0 | 5 |
| 1:00 PM | 6:00 PM | 0 | 5 |
Time Zone: individual input comparisons
| Input | Value | Time at the destination | Day shift (−1, 0 or +1) | Hours ahead of the origin |
|---|---|---|---|---|
| Time in the origin zone | 11:00 AM | 4:00 PM | 0 | 5 |
| 11:30 AM | 4:30 PM | 0 | 5 | |
| 12:00 PM | 5:00 PM | 0 | 5 | |
| 12:30 PM | 5:30 PM | 0 | 5 | |
| 1:00 PM | 6:00 PM | 0 | 5 | |
| From zone (standard time) | Hawaii (UTC−10) | 10:00 PM | 0 | 10 |
| Alaska (UTC−9) | 9:00 PM | 0 | 9 | |
| US Pacific (UTC−8) | 8:00 PM | 0 | 8 | |
| US Mountain (UTC−7) | 7:00 PM | 0 | 7 | |
| US Central (UTC−6) | 6:00 PM | 0 | 6 | |
| US Eastern (UTC−5) | 5:00 PM | 0 | 5 | |
| UTC or London (UTC+0) | 12:00 PM | 0 | 0 | |
| Central Europe (UTC+1) | 11:00 AM | 0 | -1 | |
| Eastern Europe (UTC+2) | 10:00 AM | 0 | -2 | |
| Moscow (UTC+3) | 9:00 AM | 0 | -3 | |
| Dubai (UTC+4) | 8:00 AM | 0 | -4 | |
| India (UTC+5:30) | 6:30 AM | 0 | -5.5 | |
| Bangkok (UTC+7) | 5:00 AM | 0 | -7 | |
| China or Singapore (UTC+8) | 4:00 AM | 0 | -8 | |
| Japan or Korea (UTC+9) | 3:00 AM | 0 | -9 | |
| Sydney (UTC+10) | 2:00 AM | 0 | -10 | |
| New Zealand (UTC+12) | 12:00 AM | 0 | -12 | |
| Daylight saving in the origin zone | No | 5:00 PM | 0 | 5 |
| Yes | 4:00 PM | 0 | 4 | |
| To zone (standard time) | Hawaii (UTC−10) | 7:00 AM | 0 | -5 |
| Alaska (UTC−9) | 8:00 AM | 0 | -4 | |
| US Pacific (UTC−8) | 9:00 AM | 0 | -3 | |
| US Mountain (UTC−7) | 10:00 AM | 0 | -2 | |
| US Central (UTC−6) | 11:00 AM | 0 | -1 | |
| US Eastern (UTC−5) | 12:00 PM | 0 | 0 | |
| UTC or London (UTC+0) | 5:00 PM | 0 | 5 | |
| Central Europe (UTC+1) | 6:00 PM | 0 | 6 | |
| Eastern Europe (UTC+2) | 7:00 PM | 0 | 7 | |
| Moscow (UTC+3) | 8:00 PM | 0 | 8 | |
| Dubai (UTC+4) | 9:00 PM | 0 | 9 | |
| India (UTC+5:30) | 10:30 PM | 0 | 10.5 | |
| Bangkok (UTC+7) | 12:00 AM | 1 | 12 | |
| China or Singapore (UTC+8) | 1:00 AM | 1 | 13 | |
| Japan or Korea (UTC+9) | 2:00 AM | 1 | 14 | |
| Sydney (UTC+10) | 3:00 AM | 1 | 15 | |
| New Zealand (UTC+12) | 5:00 AM | 1 | 17 | |
| Daylight saving in the destination zone | No | 5:00 PM | 0 | 5 |
| Yes | 6:00 PM | 0 | 6 |
Time Zone: values and definitions
| Quantity and definition | Value used |
|---|---|
| Time in the origin zone | 12:00 PM |
| From zone (standard time) — The offset from UTC in standard time. | US Eastern (UTC−5) |
| Daylight saving in the origin zone — Choose Yes during the months that zone has moved its clocks forward. | No |
| To zone (standard time) — The offset from UTC in standard time. | UTC or London (UTC+0) |
| Daylight saving in the destination zone — Choose Yes during the months that zone has moved its clocks forward. | No |
| Time at the destination | 5:00 PM |
| Day shift (−1, 0 or +1) | 0 |
| Hours ahead of the origin | 5 |
Time & Clock calculators: Military Time Converter Calculator, Hours and Minutes ↔ Decimal Hours Calculator, Sleep Calculator, Time Card Calculator, Add Time Calculator.
Two zones differ by a fixed number of hours, but daylight saving changes that gap for part of the year, and countries switch on different dates. Noon in New York in standard time is 5:00 PM in London in winter. In the weeks when only one side has moved its clocks, the gap is four hours, not five.
The daylight saving setting for each zone is the piece people forget.
Confirm each place's daylight saving status on the date itself. The switch dates differ, so a week in March or in late October can be off by an hour.
Compute durations on the time duration calculator, add time on the add time page, and convert formats on the military time converter. The sleep calculator can plan around jet lag by time of day. Check the date after conversion with the day of the week calculator.
What is UTC time?
Coordinated Universal Time, the global time standard from which time zones are offset. It does not observe daylight saving.
Do all places have whole-hour offsets?
No. India uses UTC plus 5:30, Nepal plus 5:45 and a few other places use half-hour or 45-minute offsets.
Why do meeting times go wrong across zones?
Because zones observe daylight saving on different dates, so the gap between two places can change by an hour for a few weeks a year.