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 world is divided into 24 primary time zones, each offset from Coordinated Universal Time (UTC) by a whole or half-hour increment. Time zones exist so that noon roughly corresponds to when the sun is highest in the sky at each location.
How UTC Offsets Work
UTC is the global time standard (formerly called GMT — Greenwich Mean Time). 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 Australia observe DST. Countries near the equator (UAE, India, China, Japan) do NOT observe DST.
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)
- Avoid scheduling calls at midnight or 5 AM in any participant’s time zone