Time Zone Converter
Time zone converter
Convert DST-aware local time or find a shared business-hours meeting window.
London
15:00
Sun, Jul 5, 2026 • UTC+1 • Offset delta +6h
Live
09:00
Chicago
Chicago
09:00
2026-07-05 · UTC-5
London
15:00
2026-07-05 · UTC+1
UTC
14:00
2026-07-05 · UTC+0
DST note: offsets shown are evaluated for this exact instant and can differ on other dates.
Optional helpers: favorites and examples
Favorite zones
Quick examples
DST boundary: nonexistent spring-forward times are rejected and repeated fall-back times require an explicit earlier/later choice.
Assumptions: zone rules come from the runtime IANA dataset; meeting mode uses a fixed 09:00–18:00 local window sampled every 30 minutes with no holiday filtering.
Formula
UTC instant = source local time - source offset; Target time = UTC instant + target offset Symbol legend
| Symbol | Meaning | Unit | Copy |
|---|---|---|---|
t_{source} | Datetime in source zone | date-time | |
\Delta | UTC offset at that instant | hours |
- Resolve the source local datetime against the source zone rules for that exact date.
- Reject spring-forward times that do not exist and require a choice when a fall-back time occurs twice.
- Convert the selected instant to UTC, then render it with the target zone offset and calendar date.
- Meeting mode samples every 30 minutes and keeps slots inside 09:00–18:00 local time for both zones.
Example
Worked example: New York to London in June
- 1 Input = 2026-06-15 09:00 in America/New_York.
- 2 New York is UTC-4 and London is UTC+1 at that instant.
- 3 The same UTC instant renders as 14:00 in London.
- 4 Their shared 09:00–18:00 working window is 09:00–13:00 New York / 14:00–18:00 London.
09:00 in New York converts to 14:00 in London with a five-hour offset difference.
How
- Choose Convert time or Meeting overlap.
- Enter the source local datetime or meeting date.
- Select source and target city zones, use favorites, or swap them.
- For a repeated fall-back time, choose the earlier or later occurrence.
- Read the converted instant or the shared 09:00–18:00 working window, then copy the result or share link.
Avoid
- Using fixed abbreviations such as CST or IST without identifying the actual IANA region.
- Ignoring a spring-forward local time that never occurred.
- Assuming a repeated fall-back time identifies one unique instant.
- Forgetting that conversion can move the target to the previous or next calendar day.
- Treating a convenient call time as a shared business-hours overlap without checking both zones.
FAQ
Does this support daylight saving time?
Yes. Offsets are evaluated for the selected date and IANA zone. Nonexistent spring-forward times are rejected, and repeated fall-back times expose earlier/later choices.
Why can date change after conversion?
Large offset differences can move time to previous or next calendar day.
Can I use this for meeting planning?
Yes. Meeting overlap mode finds 30-minute slots that fall within 09:00–18:00 local time in both selected zones.
Can I share a configured scenario?
Yes. Use Copy share link to capture mode, date/datetime, zones, and fall-back ambiguity choice in the URL.
Why does the converter use city or region zones instead of abbreviations?
Abbreviations can be ambiguous and may not encode daylight-saving rules. IANA zones such as America/Chicago or Asia/Kolkata identify the rule set.
What happens when a local time occurs twice?
During the fall-back transition, the same clock reading can map to two instants. The converter requires you to select the earlier or later occurrence.
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