Time Zone Converter

Common Examples

Input	Result
3:00 PM EST to CET	9:00 PM CET (same day)
9:00 AM PST to JST	2:00 AM JST (next day)
12:00 PM UTC to IST	5:30 PM IST (same day)
8:00 PM AEST to EST	5:00 AM EST (same day)
10:00 AM CST to GMT	4:00 PM GMT (same day)

How It Works

The Formula

Time zone conversion relies on the UTC (Coordinated Universal Time) offset difference between two zones:

Converted Time = Input Time + (Target UTC Offset - Source UTC Offset)

Where:

Input Time = the time in the source time zone
Source UTC Offset = the number of hours ahead of or behind UTC for the source zone
Target UTC Offset = the number of hours ahead of or behind UTC for the target zone

If the result exceeds 23:59, it rolls over to the next day. If it goes below 00:00, it rolls back to the previous day.

Common UTC Offsets

The standard (non-daylight-saving) offsets for the zones in this converter are:

EST (Eastern Standard Time): UTC-5
CST (Central Standard Time): UTC-6
MST (Mountain Standard Time): UTC-7
PST (Pacific Standard Time): UTC-8
UTC / GMT: UTC+0
CET (Central European Time): UTC+1
IST (India Standard Time): UTC+5:30
JST (Japan Standard Time): UTC+9
AEST (Australian Eastern Standard Time): UTC+10

Daylight Saving Time

This converter uses standard (non-DST) offsets. During daylight saving time, many zones shift by one hour. For example, EDT (Eastern Daylight Time) is UTC-4 instead of UTC-5. Adjust your source or target zone accordingly during DST periods.

Half-Hour Offsets

Some time zones use half-hour or even 45-minute offsets. India Standard Time (IST) at UTC+5:30 is the most common example. The converter handles fractional offsets correctly, converting the offset difference into the appropriate number of hours and minutes.

Worked Example

To convert 3:00 PM EST to CET: EST offset = -5, CET offset = +1. Difference = +1 - (-5) = +6 hours. Converted time = 15:00 + 6:00 = 21:00 (9:00 PM CET). Same day, no rollover. To convert 9:00 PM EST to JST: Difference = +9 - (-5) = +14 hours. Converted time = 21:00 + 14:00 = 35:00. Since 35:00 exceeds 24:00, subtract 24: 35 - 24 = 11:00 (11:00 AM JST, next day).

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Frequently Asked Questions

Does this converter account for daylight saving time?

This converter uses standard (non-DST) offsets. During daylight saving time periods (typically March to November in North America, or March to October in Europe), the affected zones shift by one hour. Adjust your selection accordingly, or check the current offset for your specific zone.

What is UTC and how is it different from GMT?

UTC (Coordinated Universal Time) is the primary time standard used worldwide. GMT (Greenwich Mean Time) is a time zone based on the Prime Meridian. For practical purposes, UTC and GMT represent the same time (UTC+0), though UTC is the modern technical standard used in computing and aviation.

Why does India have a half-hour offset?

India Standard Time (IST) is UTC+5:30, reflecting the geographic position of India between two whole-hour zones. Several other regions also use half-hour offsets, including Newfoundland (UTC-3:30), Iran (UTC+3:30), and parts of Australia (UTC+9:30).

How do I know if a time crosses into the next day?

The converter indicates day changes with a 'next day' or 'previous day' label. This happens when the converted time exceeds midnight (crosses 00:00) in either direction.

Can I convert between zones not listed here?

This converter includes the 10 most commonly referenced time zones. For other zones, determine the UTC offset and find the closest match, or use the offset difference to manually adjust. For example, AKST (Alaska) is UTC-9, one hour behind PST.