Time Zone Converter

Convert time between any two world time zones. Find meeting times, flight arrivals, or market hours across time zones.

🌍 Time Zone Converter
From Time Zone
Date & Time
To Time Zone
Converted Time
—
UTC Offset (From)
—
UTC Offset (To)
—
Time Difference
—

🌎 What are Time Zones?

The Earth is divided into 24 primary time zones, each representing a 15-degree segment of longitude (since 360 ÷ 24 = 15). As the Earth rotates, different parts experience day and night at different times. Time zones allow every region to have noon correspond roughly to when the sun is at its highest point in the sky.

The reference point is UTC (Coordinated Universal Time), formerly known as GMT (Greenwich Mean Time), set at the Prime Meridian (0° longitude) passing through Greenwich, London. Time zones to the east are ahead of UTC (positive offset), and zones to the west are behind (negative offset). India Standard Time (IST) is UTC+5:30, meaning when it is 12:00 UTC, it is 5:30 PM IST. US Eastern Standard Time (EST) is UTC−5, meaning 12:00 UTC = 7:00 AM EST.

In practice, time zone boundaries follow country and state borders rather than strict meridians, resulting in some unusual offsets. India uses a single time zone (UTC+5:30) despite its large east-west span. China uses a single UTC+8 for all its territory (Beijing to Xinjiang). Some zones are not on the hour — India (+5:30), Nepal (+5:45), Afghanistan (+4:30), and Australia's Eucla (+8:45) are examples of half- and quarter-hour offsets.

Daylight Saving Time (DST) adds another layer of complexity. About 70 countries shift their clocks forward by 1 hour in summer to extend evening daylight. The US, Canada, the UK, the EU, and Australia observe DST; India, China, Japan, and most of Asia and Africa do not. This means the time difference between two zones can change by 1 hour depending on the season. This calculator uses the browser's built-in timezone API, which automatically handles DST based on the selected date.

Time zone conversion is critical for international business meetings, global travel planning, tracking market opening hours (New York Stock Exchange opens at 9:30 AM EST = 10:00 PM IST), and for software developers handling timestamps across distributed systems.

📐 Time Zone Conversion Formula

Target Time = Source Time + (Target UTC Offset − Source UTC Offset)
Source Time = The known time in the source time zone
Target UTC Offset = Hours (and minutes) ahead (+) or behind (−) UTC for the target zone
Source UTC Offset = Hours (and minutes) ahead (+) or behind (−) UTC for the source zone
If result exceeds midnight: add or subtract 24 hours and adjust the date accordingly
Example: Convert 3:00 PM IST (UTC+5:30) to EST (UTC−5)
Offset difference = −5 − (+5.5) = −10.5 hours
Target time = 15:00 + (−10.5 hours) = 15:00 − 10:30 = 4:30 AM EST
Note: 4:30 AM is on the same date (no date rollover since we subtracted from 15:00)

📖 How to Use This Calculator

Converting a Time

1
Select the "From" time zone - the zone the original time is in. Your browser's local time zone is pre-selected.
2
Enter the date and time to convert. Today's date and current time are pre-filled.
3
Select the "To" time zone and click Convert. Use the Swap button to reverse the conversion direction.
Try: IST 9:30 AM → New York →

Example — London meeting at 3:00 PM GMT, what time in Tokyo?

1
From: GMT (UTC+0) · Time: 3:00 PM · To: JST (UTC+9)
2
Offset difference = +9 − 0 = +9 hours
3
Tokyo time = 3:00 PM + 9 hours = 12:00 AM next day
3:00 PM London (GMT) = Midnight (next day) in Tokyo (JST)
Try this example →

💡 Common Time Zone Conversions

IST (India)UTCGMT/BST (UK)EST (US East)PST (US West)JST (Japan)
12:00 AM6:30 PM prev6:30 PM prev1:30 PM prev10:30 AM prev3:30 AM
6:00 AM12:30 AM12:30 AM7:30 PM prev4:30 PM prev9:30 AM
9:00 AM3:30 AM3:30 AM10:30 PM prev7:30 PM prev12:30 PM
12:00 PM6:30 AM6:30 AM1:30 AM10:30 PM prev3:30 PM
6:00 PM12:30 PM12:30 PM7:30 AM4:30 AM9:30 PM
9:00 PM3:30 PM3:30 PM10:30 AM7:30 AM12:30 AM next

Values are for standard time (no DST). GMT = BST −1 hour in British Summer Time. EST = EDT −1 hour during US Daylight Saving. "prev" = previous calendar day.

❓ Frequently Asked Questions

What is UTC and how do time zones relate to it?+
UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks. All time zones are expressed as UTC offsets — positive for zones east of Greenwich (e.g., IST = UTC+5:30, JST = UTC+9) and negative for zones west (e.g., EST = UTC−5, PST = UTC−8). To convert: Target Time = Source Time + (Target Offset − Source Offset).
What is Daylight Saving Time (DST) and which countries observe it?+
Daylight Saving Time (DST) is the practice of advancing clocks by 1 hour during summer months to extend evening daylight. Countries that observe DST include the US (March/November), the UK and EU (last Sunday in March/October), Canada, and Australia. Many countries do NOT observe DST, including India, China, Japan, UAE, Russia, and most of Africa and Asia. This calculator uses the browser’s built-in timezone API which automatically accounts for DST.
What is the difference between IST and EST?+
IST (Indian Standard Time) is UTC+5:30. EST (Eastern Standard Time, US) is UTC−5. The difference is 5:30 + 5 = 10 hours 30 minutes, with IST ahead. So when it is 9:00 AM EST, it is 7:30 PM IST. During US Eastern Daylight Time (EDT, UTC−4), the difference reduces to 9:30 hours.
How do I find a good meeting time across multiple time zones?+
Find the overlap between standard business hours (9 AM–5 PM) in each participant’s time zone. For example, New York (EST, UTC−5) + London (GMT, UTC+0) + Mumbai (IST, UTC+5:30): 2 PM–5 PM in New York = 7 PM–10 PM in London = 12:30 AM–3:30 AM in Mumbai. A 9 AM meeting in New York = 2 PM in London = 7:30 PM in Mumbai — more reasonable for all parties.
What is the time difference between India and the US?+
India (IST, UTC+5:30) vs US Eastern (EST, UTC−5): 10.5 hours ahead. India vs US Central (CST, UTC−6): 11.5 hours ahead. India vs US Mountain (MST, UTC−7): 12.5 hours ahead. India vs US Pacific (PST, UTC−8): 13.5 hours ahead. These differences shrink by 1 hour when the US switches to daylight saving time (EDT, CDT, MDT, PDT).
What time zones are in Australia?+
Australia has 5 time zones: AWST (Perth, UTC+8), ACWST (Eucla, UTC+8:45), ACST (Adelaide, Darwin, UTC+9:30), AEST (Sydney, Melbourne, Brisbane, UTC+10), and AEDT (Sydney/Melbourne in summer, UTC+11 with DST). Australia also has external territories including Christmas Island (UTC+7) and Lord Howe Island (UTC+10:30/+11).
What is the time difference between India and Dubai?+
India (IST, UTC+5:30) and Dubai (GST, UTC+4) differ by 1 hour 30 minutes — India is ahead. When it is 10:00 AM in Dubai, it is 11:30 AM in India. The UAE does not observe daylight saving time, so this difference remains constant throughout the year.
Why do some time zones have 30-minute or 45-minute offsets?+
Most time zones are set to full-hour offsets from UTC for simplicity. However, some regions use fractional offsets for geographic or political reasons. India (UTC+5:30) uses a 30-minute offset to split the difference between its eastern and western extents. Nepal (UTC+5:45) uses a 15-minute offset to differ from India. Australia’s central zone uses UTC+9:30. Chatham Islands (New Zealand) uses UTC+12:45 or 13:45 with DST.
How do I convert between PST and IST?+
PST (Pacific Standard Time, US West Coast) is UTC−8. IST is UTC+5:30. The difference is 8 + 5.5 = 13.5 hours — IST is 13 hours 30 minutes ahead of PST. So 9:00 AM PST = 10:30 PM IST. During US Daylight Saving (PDT, UTC−7), the gap narrows to 12 hours 30 minutes: 9:00 AM PDT = 9:30 PM IST.
What is the time difference between the UK and India?+
The UK uses GMT (UTC+0) in winter and BST (British Summer Time, UTC+1) in summer. India is always UTC+5:30. In winter: India is 5 hours 30 minutes ahead (9 AM GMT = 2:30 PM IST). In summer (UK on BST): India is 4 hours 30 minutes ahead (9 AM BST = 1:30 PM IST). Note that India does not observe DST, so the gap changes only when the UK switches.
Tags: Time Zone Converter Time Zone Calculator Convert Time Zones UTC Converter World Clock IST to EST EST to IST PST to IST Time Difference GMT Converter Meeting Time Zones

🔗 Related Calculators

🎂
Age Calculator
Date & Time
📅
Date Difference Calculator
Date & Time
⏱️
Countdown Calculator
Date & Time
🕐
Work Hours Calculator
Date & Time

📌 Quick Tips

💡UTC (Coordinated Universal Time) is the world's primary time standard. All other time zones are expressed as UTC offsets - e.g., IST = UTC+5:30, EST = UTC−5.
💡When scheduling international meetings, use a 'world clock' approach: find overlapping business hours across all participants' time zones.
💡The International Date Line (roughly 180° longitude) is where the calendar date changes. East of it is one day behind; west is one day ahead.