One formula
Time difference = their UTC offset − your UTC offset
If either city observes daylight saving time, its offset changes with the season, and so does the difference.
Worked examples (as of 1 October 2026)
| City | Offset now | Changes on | Offset after |
|---|---|---|---|
| New York | UTC−4 (EDT) | 2026-11-01 | UTC−5 (EST) |
| Los Angeles | UTC−7 (PDT) | 2026-11-01 | UTC−8 (PST) |
| London | UTC+1 (BST) | 2026-10-25 | UTC+0 (GMT) |
| Paris / Berlin | UTC+2 (CEST) | 2026-10-25 | UTC+1 (CET) |
| Sydney | UTC+10 (AEST) | 2026-10-04 | UTC+11 (AEDT) |
| Tokyo / Seoul | UTC+9 | No DST | UTC+9 |
Example: 10:00 in London on 2 October is UTC 09:00 (London is UTC+1). New York (UTC−4) is 05:00 the same day; Seoul (UTC+9) is 18:00.
When the date changes
- If the result is below 0, add 24 and move the date back a day.
- If it is 24 or more, subtract 24 and move the date forward.
- The weekday moves too: Monday morning in Sydney is still Sunday afternoon in Los Angeles.
30- and 45-minute zones
| Place | Offset |
|---|---|
| India | UTC+5:30 |
| Nepal | UTC+5:45 |
| Iran | UTC+3:30 |
| Myanmar | UTC+6:30 |
| Adelaide, Australia | UTC+9:30 (UTC+10:30 in DST) |
| Newfoundland, Canada | UTC−3:30 (UTC−2:30 in DST) |
Check it in the app
Convert any moment
On the Convert tab of World Time Board, pick a From city, a date and a time, and every city you added shows its local time and date. Half-hour offsets and DST are applied for the date you chose. Copy puts the result on the clipboard as text.
Offsets and DST on the board
Each city on the Board tab shows its zone code and offset, such as EDT · UTC-4 · DST. When a change is 14 days away or less, a notice like “DST ends in 5d” appears.
FAQ
Is it 13 hours behind or 11 hours ahead?
Same position on the clock face, different date. Count in one direction consistently and adjust the date at the end.
Which countries never change their clocks?
Many, including Japan, South Korea, China and India. If the gap with one of them changes, it is the other side that moved.
World Time Board - Time Zones
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