Timezone Offset Calculator — Free
Display one instant in two IANA time zones and compare their UTC offsets. This helps coordinate international schedules without calculating elapsed travel time between a departure and arrival.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
Numbers stay on your device. Nothing is sent to a server.
How to use this tool
Enter source and destination zone names and a reference instant. An explicit UTC marker or offset makes interpretation clearer; daylight-saving behaviour follows the browser’s timezone data.
Results and examples
At the same instant, Seoul and Tokyo both use +09:00 and differ by zero minutes. A place such as New York can change offset seasonally, so another comparison date may produce a different difference.
Limitations
- Old browser timezone data may miss a recent civil-time rule change.
- Ambiguous or nonexistent local clock times require care when interpreting the input.
Fields
| Field | Guidance and constraints |
|---|---|
| From zone | UTC / New York / Chicago / Denver / Los Angeles / Anchorage / Honolulu / Toronto / Mexico City / São Paulo / London / Paris / Berlin / Madrid / Rome / Amsterdam / Stockholm / Moscow / Cairo / Johannesburg / Dubai / Kolkata / Bangkok / Singapore / Hong Kong / Shanghai / Tokyo / Seoul / Sydney / Perth / Auckland |
| To zone | UTC / New York / Chicago / Denver / Los Angeles / Anchorage / Honolulu / Toronto / Mexico City / São Paulo / London / Paris / Berlin / Madrid / Rome / Amsterdam / Stockholm / Moscow / Cairo / Johannesburg / Dubai / Kolkata / Bangkok / Singapore / Hong Kong / Shanghai / Tokyo / Seoul / Sydney / Perth / Auckland |
| Instant (ISO or empty for now) | Check the unit and format displayed beside this field. |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
What is the difference between Seoul and Tokyo?
At the same instant, Seoul and Tokyo both use +09:00 and differ by zero minutes. A place such as New York can change offset seasonally, so another comparison date may produce a different difference.
Can the offset difference change with the date?
Old browser timezone data may miss a recent civil-time rule change. Ambiguous or nonexistent local clock times require care when interpreting the input.
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