Time Zone Difference Calculator
Calculate the hours difference between two time zones using UTC offsets.
Find out what time it is in another city or country when scheduling calls and meetings.
Understanding Time Zones
The map is drawn as 24 hour-wide bands, but about 38 distinct offsets are actually in use, because a fair number of countries sit on a half hour or a quarter hour rather than a whole one. Time zones exist so that noon roughly corresponds to when the sun is highest in the sky, and every exception to the 24-band picture comes from a government deciding that convenience matters more than the sun.
How UTC Offsets Work
UTC is the global time standard, and it replaced GMT (Greenwich Mean Time) as the reference everything else is measured against. Every time zone is expressed as UTC+ or UTC− followed by hours, and sometimes minutes.
| Location | UTC Offset | Notes |
|---|---|---|
| London (winter) | UTC+0 | GMT / WET |
| London (summer) | UTC+1 | BST (daylight saving) |
| New York (winter) | UTC−5 | EST |
| New York (summer) | UTC−4 | EDT |
| Paris (winter) | UTC+1 | CET |
| Dubai | UTC+4 | No daylight saving |
| Mumbai | UTC+5:30 | 30-minute offset |
| Singapore | UTC+8 | SGT |
| Tokyo | UTC+9 | JST |
| Sydney (summer) | UTC+11 | AEDT |
| Los Angeles (winter) | UTC−8 | PST |
| Los Angeles (summer) | UTC−7 | PDT |
The Difference Formula
Difference = UTC Offset of Location B − UTC Offset of Location A
If Location A is UTC−5 and Location B is UTC+2: Difference = 2 − (−5) = +7 hours
This means Location B is 7 hours ahead of Location A.
Daylight Saving Time (DST)
Many countries shift their clocks forward by 1 hour in summer (spring forward, fall back). This means the offset changes twice a year. The United States, Canada, Europe, and much of Australia observe DST. India, China, Japan, the UAE and most of Africa and South America do not.
Latitude is the usual explanation given for this and it is only half right. Near the equator the day barely changes length, so there is nothing to save. But Japan sits at the same latitude as Los Angeles and still does not observe DST, having tried it under the American occupation and abandoned it in 1952. Brazil dropped it in 2019. Whether a country changes its clocks is a political decision, not a geographic one, which is exactly why you cannot infer it and have to look it up.
The three weeks each March and October when Europe and the United States have switched on different weekends are when most scheduling mistakes happen. The offset you memorised is briefly wrong by an hour.
Scheduling Across Time Zones
When scheduling international calls:
- Find a time that is business hours for all participants
- USA (East Coast) + Europe: 9–10 AM ET = 3–4 PM CET (works well)
- USA (West Coast) + Asia: morning PST = evening in Asia (challenging)
- New York and Tokyo are 14 hours apart in winter and 13 in summer, and have no overlap in normal working hours at all. Somebody has to take the call early or late; the only fair answer is to rotate who
- Avoid scheduling calls at midnight or 5 AM in any participant’s time zone
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.