# Time Zone Calculator

> Convert a date and time from one time zone to another, with daylight saving time applied for that date and the UTC offsets of both places.

Category: Date, time & lifestyle · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/time-zone-calculator

Choose a date, a time and two places. The conversion uses the IANA time zone database built into your browser, so daylight saving time is applied for the exact date you enter.

Also called: Time zone converter, World time converter.

## Inputs
- Date (default 2026-07-01)
- Time (default 12:00)
- From (options: UTC (Coordinated Universal Time), Honolulu (Pacific/Honolulu), Anchorage (America/Anchorage), Los Angeles, Pacific (America/Los_Angeles), Denver, Mountain (America/Denver), Phoenix, Arizona (America/Phoenix), Chicago, Central (America/Chicago), New York, Eastern (America/New_York), Toronto (America/Toronto), Mexico City (America/Mexico_City), Bogotá (America/Bogota), São Paulo (America/Sao_Paulo), Buenos Aires (America/Argentina/Buenos_Aires), Reykjavík (Atlantic/Reykjavik), London (Europe/London), Dublin (Europe/Dublin), Lisbon (Europe/Lisbon), Paris (Europe/Paris), Berlin (Europe/Berlin), Madrid (Europe/Madrid), Rome (Europe/Rome), Amsterdam (Europe/Amsterdam), Stockholm (Europe/Stockholm), Warsaw (Europe/Warsaw), Athens (Europe/Athens), Istanbul (Europe/Istanbul), Moscow (Europe/Moscow), Cairo (Africa/Cairo), Johannesburg (Africa/Johannesburg), Lagos (Africa/Lagos), Nairobi (Africa/Nairobi), Dubai (Asia/Dubai), Karachi (Asia/Karachi), India (Asia/Kolkata), Kathmandu (Asia/Kathmandu), Dhaka (Asia/Dhaka), Bangkok (Asia/Bangkok), Jakarta (Asia/Jakarta), Singapore (Asia/Singapore), Hong Kong (Asia/Hong_Kong), China (Asia/Shanghai), Manila (Asia/Manila), Seoul (Asia/Seoul), Tokyo (Asia/Tokyo), Perth (Australia/Perth), Adelaide (Australia/Adelaide), Brisbane (Australia/Brisbane), Sydney (Australia/Sydney), Auckland (Pacific/Auckland); default America/New_York)
- To (options: UTC (Coordinated Universal Time), Honolulu (Pacific/Honolulu), Anchorage (America/Anchorage), Los Angeles, Pacific (America/Los_Angeles), Denver, Mountain (America/Denver), Phoenix, Arizona (America/Phoenix), Chicago, Central (America/Chicago), New York, Eastern (America/New_York), Toronto (America/Toronto), Mexico City (America/Mexico_City), Bogotá (America/Bogota), São Paulo (America/Sao_Paulo), Buenos Aires (America/Argentina/Buenos_Aires), Reykjavík (Atlantic/Reykjavik), London (Europe/London), Dublin (Europe/Dublin), Lisbon (Europe/Lisbon), Paris (Europe/Paris), Berlin (Europe/Berlin), Madrid (Europe/Madrid), Rome (Europe/Rome), Amsterdam (Europe/Amsterdam), Stockholm (Europe/Stockholm), Warsaw (Europe/Warsaw), Athens (Europe/Athens), Istanbul (Europe/Istanbul), Moscow (Europe/Moscow), Cairo (Africa/Cairo), Johannesburg (Africa/Johannesburg), Lagos (Africa/Lagos), Nairobi (Africa/Nairobi), Dubai (Asia/Dubai), Karachi (Asia/Karachi), India (Asia/Kolkata), Kathmandu (Asia/Kathmandu), Dhaka (Asia/Dhaka), Bangkok (Asia/Bangkok), Jakarta (Asia/Jakarta), Singapore (Asia/Singapore), Hong Kong (Asia/Hong_Kong), China (Asia/Shanghai), Manila (Asia/Manila), Seoul (Asia/Seoul), Tokyo (Asia/Tokyo), Perth (Australia/Perth), Adelaide (Australia/Adelaide), Brisbane (Australia/Brisbane), Sydney (Australia/Sydney), Auckland (Pacific/Auckland); default Europe/London)

## Results
- Converted time
- Same moment in UTC
- Source offset on that date
- Target offset on that date
- Target is ahead by

## Formula

```
UTC = Local time − Source offset;  Target time = UTC + Target offset. Offsets come from the IANA time zone database for that exact instant, including daylight saving time.
```

Where:
- Offset: hours ahead of (+) or behind (−) UTC at that moment

## Worked example
1. On 1 July New York is on daylight time (EDT), UTC−4, so 12:00 there is 16:00 UTC.
2. London is on British Summer Time, UTC+1, so 16:00 UTC is 17:00.
3. London is 5 hours ahead of New York on that date.

**Result:** Noon in New York on 1 July 2026 is 5 pm the same day in London.

## What the result means

The difference between two places can change during the year because countries start and end daylight saving time on different dates (for example, the US and UK change clocks on different weekends in March and autumn).

## Assumptions and limits
- Time zone rules are those in the IANA database shipped with your browser.
- A local time that is skipped when clocks go forward cannot be converted; a time that happens twice when clocks go back uses the first occurrence.
- Future dates use today’s known rules; governments sometimes change them at short notice.

## Questions

### Why is the difference between New York and London sometimes 4 hours?

The US moves its clocks forward on the second Sunday of March and back on the first Sunday of November, while the UK changes on the last Sundays of March and October. In the weeks between, the gap is 4 hours instead of 5.

### Does India use daylight saving time?

No. India uses UTC+05:30 all year, so its difference from places that do use daylight saving time changes by an hour twice a year.

## Related calculators
- [Time Calculator](https://calculators.geekmidst.com/calculators/time-calculator)
- [Date Calculator](https://calculators.geekmidst.com/calculators/date-calculator)
- [Date Difference Calculator](https://calculators.geekmidst.com/calculators/date-difference-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/time-zone-calculator