Time Zone Converter

Find the perfect meeting time and convert clocks across every world time zone. Click any hour block to select your meeting time, then see it instantly reflected across all your added cities.

Your current local time: --:--:-- Detecting location...

Select meeting hour: Local 12:00 PM

Key:

Business hours (9 AM - 5 PM) - ideal overlap

Daytime (outside business hours)

Nighttime (10 PM - 6 AM) - avoid if possible

Selected meeting time

Add a time zone above to begin planning your meeting.

Selected Meeting Time Across All Zones:

The Ultimate Guide to Global Time Zones and Scheduling

Whether you are coordinating a client call between New York and Singapore, running a daily standup across Europe and Asia, or simply figuring out the best time to call family abroad, understanding time zones is a fundamental skill in today's connected world. This guide explains every core concept you need - from UTC offsets and DST transitions to practical scheduling strategies for globally distributed teams.

Key Terminology Explained

UTC - Coordinated Universal Time

The primary world time standard. Not a time zone itself, but the universal baseline that all other zones are measured against. UTC is defined by atomic clocks and never observes Daylight Saving Time, making it the stable reference used by aviation, the internet, and financial systems.

GMT - Greenwich Mean Time

The mean solar time at the Royal Observatory in Greenwich, London, established in 1884. In everyday scheduling, GMT and UTC are treated as identical. Technically, GMT is an astronomical measurement while UTC is atomic-clock based, but they never differ by more than one second.

UTC Offset

A positive or negative value showing how many hours (and sometimes minutes) a location is ahead of or behind UTC. For example: New York in winter is UTC-5 (five hours behind), Tokyo is UTC+9 (nine hours ahead), and India is UTC+5:30 (five and a half hours ahead).

DST - Daylight Saving Time

A seasonal practice of advancing clocks by one hour in spring and setting them back in autumn to make better use of evening daylight. Approximately 70 countries observe DST, but on different schedules. Many regions including Japan, China, India, and most of Africa do not observe DST at all.

IANA Time Zone Database

The authoritative, regularly updated database of world time zone rules. It uses location identifiers such as "America/New_York" or "Asia/Tokyo" and is used by all modern browsers, operating systems, and programming languages to correctly account for DST and historical changes.

Half-Hour and 45-Minute Offsets

Some regions use non-whole-hour UTC offsets. India (UTC+5:30), Sri Lanka (UTC+5:30), Nepal (UTC+5:45), and parts of Australia (UTC+9:30) are notable examples. This means a meeting at 10:00 AM UTC is 3:30 PM in Mumbai, not 3:00 PM or 4:00 PM as a simple hour-based calculation would suggest.

Standard UTC Offsets Cheat Sheet - Major Global Hubs

Standard (winter) offsets are listed. Where Daylight Saving Time applies, the summer offset is shown separately. Actual offsets in this tool always reflect the live current offset.

City / Region	Abbreviation	Standard Offset	DST Offset	DST Observed	Notes
Honolulu, USA	HST	UTC-10	None	No DST	Hawaii does not observe Daylight Saving Time
Anchorage, USA	AKST/AKDT	UTC-9	UTC-8	Mar to Nov	Alaska observes standard US DST schedule
Los Angeles, USA	PST/PDT	UTC-8	UTC-7	Mar to Nov	US Pacific coast
Denver, USA	MST/MDT	UTC-7	UTC-6	Mar to Nov	Mountain US (Phoenix stays UTC-7 year-round)
Chicago, USA	CST/CDT	UTC-6	UTC-5	Mar to Nov	Central US
New York, USA	EST/EDT	UTC-5	UTC-4	Mar to Nov	US East coast - most common reference point
Sao Paulo, Brazil	BRT/BRST	UTC-3	UTC-2	Varies	Brazil has changed its DST policy several times
London, UK	GMT/BST	UTC+0	UTC+1	Mar to Oct	British Summer Time applies in summer months
Paris, Berlin, Rome	CET/CEST	UTC+1	UTC+2	Mar to Oct	Central European Time - most of continental Europe
Helsinki, Athens	EET/EEST	UTC+2	UTC+3	Mar to Oct	Eastern European Time zone
Moscow, Russia	MSK	UTC+3	None	No DST (since 2014)	Russia permanently abolished DST in 2014
Dubai, UAE	GST	UTC+4	None	No DST	Gulf Standard Time - stable year-round
Karachi, Pakistan	PKT	UTC+5	None	No DST	Pakistan Standard Time
Mumbai, Delhi, India	IST	UTC+5:30	None	No DST	India uses a single half-hour offset for the entire country
Kathmandu, Nepal	NPT	UTC+5:45	None	No DST	One of only three countries using a 45-minute offset
Dhaka, Bangladesh	BST	UTC+6	None	No DST	Bangladesh Standard Time
Bangkok, Thailand	ICT	UTC+7	None	No DST	Indochina Time - also covers Vietnam and Cambodia
Singapore, HK, China	SGT/HKT/CST	UTC+8	None	No DST	All of China uses UTC+8 (Beijing Time) nationally
Tokyo, Japan	JST	UTC+9	None	No DST	Japan does not observe DST - stable reference point
Adelaide, Australia	ACST/ACDT	UTC+9:30	UTC+10:30	Oct to Apr	Southern hemisphere DST runs opposite to northern
Sydney, Melbourne	AEST/AEDT	UTC+10	UTC+11	Oct to Apr	Australian Eastern Time - DST in southern summer
Auckland, New Zealand	NZST/NZDT	UTC+12	UTC+13	Sep to Apr	First major city to greet each new calendar day

How to Calculate a Time Zone Difference Manually

To manually calculate a time difference between two cities, look up both cities' current UTC offsets, then subtract one from the other. The result is the number of hours to add or subtract. For example, New York in summer (UTC-4) and London in summer (UTC+1) have a difference of +1 minus (-4) = 5 hours. When it is 9:00 AM in New York, it is 2:00 PM in London.

Complications arise when both cities observe Daylight Saving Time on different schedules. In the brief window each March after the United States springs forward but before the European Union does (typically a two to three week gap), the New York to London offset temporarily shrinks from 5 hours to 4 hours. Similarly, in autumn the US stays on summer time for about a week longer than the EU, creating another brief window of unusual offsets. This is why automated tools are essential - they always apply the live, current offset rather than a static assumption.

For calculations that cross midnight, remember to account for the date change. If it is 10:00 PM in Los Angeles (UTC-8 in winter), the UTC time is 6:00 AM the next morning. Tokyo (UTC+9) would then be at 3:00 PM the same day as the UTC morning - but a full day ahead of Los Angeles's date. Always confirm whether the foreign city is on the next calendar day or the previous one, as this affects flight connections, contract deadlines, and international wire transfers.

A practical tip for recurring global meetings: Schedule meetings in UTC and convert to local time for each participant. This removes all ambiguity, especially during the DST transition weeks when offsets between specific pairs of cities briefly change. Sending calendar invites with a UTC reference time and multiple local time notations (e.g., "3:00 PM UTC / 11:00 AM EDT / 4:00 AM JST next day") prevents missed calls and confusion for all parties.