Timezone Converter
Convert any date and time between world timezones instantly. View live clocks for major cities, understand UTC offsets, and plan meetings across international timezones. Free, fast, and completely private.
Current Time in Major Cities
What You Get
Instant Timezone Conversion
Convert any date and time between 16 major world timezones with a single click. The converter uses the native JavaScript Intl API with IANA timezone identifiers, ensuring that daylight saving time transitions, historical offset changes, and regional variations are handled automatically and accurately. Select your source and target timezones from the dropdown menus, enter a date and time, and receive the converted result instantly.
Live World Clocks
Monitor the current time in ten major cities around the globe in real time. The world clock display updates every second and shows the time, date, and day of the week for New York, London, Tokyo, Sydney, Dubai, Los Angeles, Berlin, Singapore, Mumbai, and Sao Paulo. This feature is ideal for distributed teams, international travelers, and anyone who needs to track multiple timezones at a glance.
Automatic DST Handling
Daylight saving time rules differ between countries and change periodically with legislation. This converter relies on your browser's built-in timezone database, which is regularly updated by operating system vendors. Whether you are converting a summer date in New York (EDT, UTC-4) or a winter date (EST, UTC-5), the correct offset is applied automatically without any manual adjustment required on your part.
Swap & Compare
Quickly reverse the direction of your conversion with the swap button positioned between the timezone selectors. This is especially useful when coordinating meetings across timezones — check what time it is for you when a colleague proposes a meeting, then swap to see what time your preferred slot would be for them. The conversion result updates instantly each time you change any input.
Step-by-Step Guide
- Enter a date and time — Use the datetime picker to select the date and time you want to convert. By default, the current date and time are pre-filled for your convenience.
- Select the source timezone — Choose the timezone your original time is in from the "From Timezone" dropdown. The list includes 16 major timezones with their UTC offsets and common abbreviations.
- Select the target timezone — Choose the timezone you want to convert to from the "To Timezone" dropdown. You can use the swap button between the dropdowns to quickly reverse the direction.
- Click Convert — The converted date and time appear instantly below the inputs, along with details about the UTC offsets of both timezones and the time difference between them. Results update in real time whenever you change any input.
- Check world clocks — Scroll down within the tool to see the current time in ten major cities, updated every second. Use this to quickly reference what time it is anywhere in the world right now.
Daylight Saving Time shifts happen on different dates worldwide. The US springs forward in March, the EU in late March, and Australia in October. Always use IANA timezone identifiers (like America/New_York) instead of fixed UTC offsets, which do not account for DST transitions.
Assuming EST means the same as Eastern Time. EST (UTC-5) is the fixed offset for winter only. During summer, Eastern Time becomes EDT (UTC-4). Using "EST" year-round causes meetings to be off by one hour for half the year.
Understanding World Timezones
The concept of standardized timezones is relatively modern in the context of human history. Before the late nineteenth century, cities and towns set their clocks according to local solar time, meaning that noon occurred when the sun was at its highest point in the sky for that specific location. A town just fifty miles to the east or west would have a slightly different local time. This worked well enough when travel was slow, but the rapid expansion of railway networks in the 1800s created enormous scheduling problems. Trains running on dozens of different local times led to confusion, missed connections, and even accidents.
In 1884, delegates from 25 nations gathered at the International Meridian Conference in Washington, D.C. and established the Greenwich meridian as the prime meridian, the zero-degree line of longitude from which all other timezones would be measured. The world was divided into 24 standard timezones, each spanning approximately 15 degrees of longitude and representing a one-hour difference from its neighbors. Greenwich Mean Time, based on astronomical observations at the Royal Observatory in Greenwich, England, became the global reference.
Today, the scientific community uses Coordinated Universal Time, abbreviated as UTC, as the primary time standard. UTC is maintained by a network of over 400 atomic clocks distributed across more than 80 national laboratories worldwide. Unlike GMT, which is based on the rotation of the Earth, UTC is based on International Atomic Time with occasional leap seconds added to keep it synchronized with the Earth's slightly irregular rotation. For all practical purposes, UTC and GMT show the same time, but UTC is the technically precise standard used in computing, aviation, meteorology, and international treaties.
One of the most confusing aspects of timezones is daylight saving time. The idea of shifting clocks forward in spring and back in autumn was first seriously proposed by George Vernon Hudson, a New Zealand entomologist, in 1895. Germany became the first country to implement DST in 1916 as a wartime energy-saving measure. Today, approximately 70 countries observe some form of DST, though the practice remains controversial. Proponents argue it saves energy and provides more usable daylight in the evening, while critics cite disrupted sleep patterns, increased health risks, and minimal actual energy savings. The European Union voted in 2019 to allow member states to stop observing DST, though implementation has been delayed.
For software developers and anyone working with time programmatically, the IANA timezone database — also known as the tz database or Olson database — is the authoritative source for timezone rules. Maintained by a community of volunteers and distributed with most operating systems, the database contains the complete history of timezone offsets, DST transitions, and naming conventions for every region on Earth. It uses a Region/City naming format such as America/New_York or Asia/Tokyo, which eliminates the ambiguity of abbreviations like CST (which could mean Central Standard Time in the US, China Standard Time, or Cuba Standard Time). This converter uses IANA timezone names through the JavaScript Intl.DateTimeFormat API, ensuring that every conversion respects the full history of timezone rules.
When scheduling international meetings or planning travel across timezones, a few practical tips can help you avoid confusion. Always specify the timezone when communicating times — saying "3 PM ET" is much clearer than just "3 PM." Use UTC as a common reference when coordinating between more than two timezones. Be aware of DST transitions, which typically occur in March and November in the Northern Hemisphere and at opposite times in the Southern Hemisphere. Finally, remember that not all timezones are whole-hour offsets from UTC — India operates at UTC+5:30, Nepal at UTC+5:45, and several other regions use half-hour or quarter-hour offsets.
Practical Applications
Remote Team Scheduling a Global Standup
A distributed team with members in New York, London, and Tokyo needs to find a meeting time that falls within business hours for all three locations. The converter reveals that 9 AM ET is 2 PM GMT and 11 PM JST — making it clear they need to rotate meeting times.
Trader Monitoring Market Opening Times
A forex trader tracks opening and closing times of exchanges in different time zones. The Tokyo, London, and New York sessions overlap at specific hours that create the highest liquidity and volatility windows.
Traveler Planning International Calls
Someone traveling from San Francisco to Berlin needs to know when they can call family back home without waking them up. With a 9-hour difference, they check which hours overlap between their evening in Europe and morning on the West Coast.
Common Questions
How do I convert a time from one timezone to another?
Enter the date and time you want to convert, select the source timezone from the "From" dropdown, and select the target timezone from the "To" dropdown. Click Convert and the result appears instantly, showing the converted time along with the UTC offsets of both timezones and the time difference between them. Use the swap button to quickly reverse the conversion direction. The converter uses IANA timezone identifiers and your browser's built-in timezone database for accuracy.
How do I find a meeting time that works across multiple timezones?
Convert your preferred meeting time from your local timezone to each participant's timezone. Check whether the converted time falls within business hours (typically 9 AM to 6 PM) for all locations. The world clocks section at the bottom shows current times in ten major cities for quick reference. If no single time works, consider rotating meeting times across weeks so no single timezone consistently bears the inconvenience of early or late calls.
Does this converter automatically handle daylight saving time changes?
Yes. The converter uses the JavaScript Intl.DateTimeFormat API with IANA timezone identifiers like America/New_York and Europe/London. Your browser's timezone database contains complete DST rules, including historical changes and future transitions. When you enter a date, the converter applies the correct UTC offset for that exact moment. A July conversion from New York uses EDT (UTC-4), while a January conversion uses EST (UTC-5). You never need to manually adjust for DST.
Why should I use IANA timezone names instead of abbreviations like EST or IST?
Timezone abbreviations are ambiguous. IST can mean Indian Standard Time (UTC+5:30), Irish Standard Time (UTC+1), or Israel Standard Time (UTC+2). CST could be Central Standard Time (US), China Standard Time, or Cuba Standard Time. IANA names like Asia/Kolkata, Europe/Dublin, and America/Chicago are globally unique and also encode DST rules automatically. This converter uses IANA names internally to ensure every conversion is precise and unambiguous.
How do half-hour and quarter-hour timezone offsets work?
Not all timezones use whole-hour offsets from UTC. India operates at UTC+5:30, Nepal at UTC+5:45, Myanmar at UTC+6:30, and the Chatham Islands at UTC+12:45. These non-standard offsets exist because countries chose to split the difference between adjacent timezone bands for geographic or political reasons. The converter handles all of these offsets correctly through the IANA timezone database, which tracks over 400 unique timezone identifiers worldwide.
Can I see the current time in multiple cities at once?
Yes. Scroll down within the tool to the world clocks section, which displays the current time in ten major cities updated every second. Cities include New York, London, Tokyo, Sydney, Dubai, and more. This live reference makes it easy to check what time it is anywhere in the world right now without performing individual conversions. All clock data comes from your browser's built-in timezone support — no external API calls are made.
World Time Zones Explained
The world is divided into time zones based on offsets from Coordinated Universal Time (UTC), the global time standard maintained by atomic clocks. Understanding the key concepts behind time zones helps avoid scheduling errors in our increasingly connected world.
UTC vs GMT
UTC (Coordinated Universal Time) and GMT (Greenwich Mean Time) represent the same time in practice, but they are defined differently. GMT is a time zone based on the mean solar time at the Royal Observatory in Greenwich, London. UTC is a precise scientific standard maintained by a network of atomic clocks worldwide, accurate to within billionths of a second. UTC is the standard used in computing, aviation, and international coordination. GMT is still used colloquially in the UK and as a time zone label.
Daylight Saving Time (DST)
Many countries shift their clocks forward by one hour in spring and back in fall to extend evening daylight during warmer months. This means the UTC offset for a city can change twice a year. Not all regions observe DST: most of Africa, Asia, and South America do not, and even within countries that do, some states or territories opt out (such as Arizona in the United States). DST transitions are the most common source of scheduling bugs in software.
| Time Zone | UTC Offset | Major Cities | DST |
|---|---|---|---|
| PST / PDT | UTC-8 / UTC-7 | Los Angeles, San Francisco, Seattle | Yes |
| EST / EDT | UTC-5 / UTC-4 | New York, Toronto, Miami | Yes |
| GMT / BST | UTC+0 / UTC+1 | London, Dublin, Lisbon | Yes |
| CET / CEST | UTC+1 / UTC+2 | Berlin, Paris, Rome, Madrid | Yes |
| IST | UTC+5:30 | Mumbai, Delhi, Bangalore | No |
| CST (China) | UTC+8 | Beijing, Shanghai, Singapore | No |
| JST | UTC+9 | Tokyo, Seoul, Osaka | No |
| AEST / AEDT | UTC+10 / UTC+11 | Sydney, Melbourne, Brisbane | Varies by state |
Note that some time zones use non-standard half-hour or 45-minute offsets. India (UTC+5:30), Nepal (UTC+5:45), and the Chatham Islands of New Zealand (UTC+12:45) are notable examples. When scheduling international meetings, always specify the UTC offset explicitly rather than using abbreviations, since abbreviations like CST refer to different zones in different countries.