With remote teams spanning multiple continents and global business relationships increasingly common, time zone conversion is an everyday skill. Scheduling a call with someone in Tokyo when you're in London, or figuring out when a US product launch starts in your local time — a time zone converter makes it immediate and error-free.
How to Convert Time Zones for Free
iConvertU's Time Zone Converter converts any time between any two time zones instantly.
Step by step
- Open iConvertU Time Zone Converter
- Enter the time and date you want to convert
- Select the source time zone
- Select the target time zone
- See the converted time and date
No account required. Conversion uses your browser's built-in timezone data.
Major World Time Zones
| Time Zone | Offset | Cities |
|---|---|---|
| UTC | ±0:00 | Coordinated Universal Time (reference) |
| GMT | ±0:00 | London (winter), Reykjavik |
| EST | UTC−5 | New York, Miami, Toronto (winter) |
| EDT | UTC−4 | New York, Miami, Toronto (summer/DST) |
| CST | UTC−6 | Chicago, Dallas, Mexico City (winter) |
| PST | UTC−8 | Los Angeles, Seattle, Vancouver (winter) |
| PDT | UTC−7 | Los Angeles, Seattle, Vancouver (summer) |
| CET | UTC+1 | Berlin, Paris, Rome (winter) |
| CEST | UTC+2 | Berlin, Paris, Rome (summer/DST) |
| IST | UTC+5:30 | Mumbai, Delhi, Bangalore |
| CST | UTC+8 | Beijing, Shanghai, Singapore |
| JST | UTC+9 | Tokyo, Osaka |
| AEST | UTC+10 | Sydney, Melbourne (winter) |
| AEDT | UTC+11 | Sydney, Melbourne (summer) |
Understanding Daylight Saving Time (DST)
Daylight Saving Time shifts clocks forward by one hour in spring and back in autumn, meaning the offset between two zones can change twice a year. This is a common source of scheduling errors.
Countries that observe DST: - United States: second Sunday in March → first Sunday in November - European Union: last Sunday in March → last Sunday in October - United Kingdom: same as EU - Australia: first Sunday in October → first Sunday in April (opposite hemisphere — their summer is our winter)
Countries that do NOT observe DST: - India (IST — always UTC+5:30) - China (CST — always UTC+8) - Japan (JST — always UTC+9) - Most of Africa and Southeast Asia
Practical impact: In March, when the US moves to EDT (UTC−4) but the EU hasn't yet moved to CEST (UTC+2), the New York → London gap temporarily shrinks from 5 hours to 4 hours for about a week.
Always verify with a time zone converter when scheduling across DST boundaries — don't rely on a fixed offset you've memorised.
Finding Meeting Times for Distributed Teams
The biggest challenge with distributed teams is finding overlap between business hours across widely separated time zones. Some useful overlaps:
| Time Zone Pair | Overlap in Business Hours |
|---|---|
| New York (EST) & London (GMT) | 13:00–17:00 EST = 18:00–22:00 GMT — difficult |
| New York (EST) & London (BST, summer) | 13:00–17:00 EST = 18:00–22:00 BST — still difficult |
| London (GMT) & Mumbai (IST) | 10:00–14:30 GMT = 15:30–19:30 IST — workable |
| London (GMT) & Singapore (SGT) | 09:00–10:00 GMT = 17:00–18:00 SGT — very limited |
| San Francisco (PST) & Tokyo (JST) | No working-hours overlap |
Time Zone Abbreviations: The Ambiguity Problem
Time zone abbreviations are not standardised globally and can be ambiguous:
- CST = Central Standard Time (UTC−6) in the US and China Standard Time (UTC+8) in China
- IST = Indian Standard Time (UTC+5:30), Israeli Standard Time (UTC+2), or Irish Standard Time (UTC+1)
For unambiguous communication, use UTC offsets: "let's meet at 14:00 UTC" is clear to everyone. Or specify city: "14:00 London time" is understood as GMT or BST depending on the season.
UTC: The Universal Reference
UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks. It has no daylight saving time adjustments. When scheduling globally, expressing times in UTC eliminates ambiguity — everyone can convert UTC to their local time without confusion about DST.
In technical contexts (server logs, API timestamps, database entries), always store times in UTC and convert to local time for display.
Frequently Asked Questions
What is the difference between UTC and GMT? For most practical purposes, UTC and GMT are the same — both are at offset ±0:00. Technically, GMT is a time zone (used in the UK in winter) and UTC is the modern international time standard. They differ by fractions of a second due to UTC's use of atomic clocks.
Why do some countries have half-hour or quarter-hour offsets? Political and historical reasons. India (UTC+5:30), Nepal (UTC+5:45), Iran (UTC+3:30), and Myanmar (UTC+6:30) all use non-integer offsets. Some parts of Australia use UTC+9:30 (ACST) or UTC+10:30 (ACDT).
How do I avoid scheduling errors with DST? Use a time zone converter that applies current DST rules rather than a fixed offset. State times in UTC for internationally distributed communications. And always double-check a few days before a meeting that crosses DST boundaries.
Is the tool free? Yes. iConvertU Time Zone Converter is completely free. No account required.
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