Time Zone Converter

Convert time between different time zones instantly. Select source and target zones to see the converted time.

Key features

Major time zones
Offset calculation
Real-time conversion
Common zone presets

Guide

Time zones divide the world into regions that observe the same standard time. Converting between time zones is a daily necessity for anyone who works with international teams, schedules calls across countries, plans travel, or follows events broadcast from other regions. This guide covers how time zones work, the key rules and exceptions, and practical strategies for managing time across zones. The world is divided into 24 primary time zones, each roughly 15 degrees of longitude wide, corresponding to one hour of Earth's rotation. Coordinated Universal Time (UTC, formerly GMT) serves as the reference point. Zones east of the prime meridian are ahead of UTC (UTC+1, UTC+2, etc.) and zones west are behind (UTC-1, UTC-2, etc.). The International Date Line, roughly following the 180-degree meridian in the Pacific Ocean, is where the calendar date changes. UTC and GMT are often used interchangeably in casual conversation, but they are technically different. GMT is a time zone (used in the UK during winter). UTC is a time standard based on atomic clocks, not tied to any location. UTC does not observe daylight saving time. When precision matters, use UTC. In practice, UTC+0 and GMT refer to the same clock time except during extremely rare leap second adjustments. Real-world time zones do not follow clean longitudinal lines. Political boundaries, economic ties, and practical considerations cause zones to zigzag around country and state borders. China, which spans five geographic time zones, uses a single time zone (UTC+8) nationwide. This means sunrise in western China can be as late as 10:00 AM. India uses UTC+5:30, a half-hour offset. Nepal uses UTC+5:45, a 45-minute offset. The Chatham Islands in New Zealand use UTC+12:45. These non-standard offsets mean you cannot simply count hours from UTC. You need the actual offset for each specific zone. Daylight Saving Time (DST) complicates conversions by shifting clocks forward one hour in spring and back one hour in fall. Not all countries observe DST. Most of the United States, Canada, and Europe observe it, but Arizona (except the Navajo Nation), Hawaii, and most tropical countries do not. Countries in the Southern Hemisphere that observe DST shift their clocks on different dates than Northern Hemisphere countries, since their seasons are reversed. Australia shifts clocks in October and April. The US and Canada shift in March and November. Europe shifts in March and October. The spring-forward transition creates a gap in local time. When clocks move from 2:00 AM to 3:00 AM, the hour between 2:00 and 3:00 does not exist. Appointments scheduled at 2:30 AM on this date never occur. The fall-back transition creates an overlap. When clocks move from 2:00 AM back to 1:00 AM, the hour between 1:00 and 2:00 happens twice. An event at 1:30 AM is ambiguous. This causes real problems for scheduling systems, transportation timetables, and any software that processes local times. DST transition dates change the UTC offset temporarily. US Eastern Time is UTC-5 in winter (EST) and UTC-4 in summer (EDT). Central European Time is UTC+1 in winter (CET) and UTC+2 in summer (CEST). During the few weeks when one region has changed clocks but another has not yet changed, the time difference between them shifts. The US-to-Europe time difference is typically 6 hours, but during the transition weeks it can be 5 or 7 hours. Always verify the current offset rather than assuming a fixed difference. The IANA time zone database (also called the tz database or Olson database) is the authoritative source for time zone rules. It uses location-based identifiers like America/New_York, Europe/London, Asia/Tokyo, and Pacific/Auckland. These identifiers encode the full history of time zone changes, DST transitions, and political boundary adjustments for each region. Software libraries that reference this database handle conversions correctly, including historical dates. The database is maintained by volunteers and updated several times per year as countries change their time zone rules. Converting a specific time between zones requires three pieces of information: the source time, the source zone's UTC offset, and the target zone's UTC offset. Convert the source time to UTC by subtracting the source offset, then add the target offset. To convert 3:00 PM US Eastern (UTC-5) to Japan Standard Time (UTC+9): 3:00 PM minus (-5 hours) gives 8:00 PM UTC. 8:00 PM UTC plus 9 hours gives 5:00 AM the next day JST. The 14-hour difference means scheduling calls between New York and Tokyo is challenging because their business hours barely overlap. A practical shortcut for frequent conversions: memorize the offset between your local zone and the zones you interact with most. If you are in New York and regularly work with colleagues in London (5 hours ahead in winter, 4 in summer) and San Francisco (3 hours behind year-round since both observe DST), you can do the mental math quickly. Write these offsets on a sticky note near your monitor until they become automatic. Date line crossings add or subtract a full day. When converting westward across the International Date Line, add a day. When converting eastward, subtract a day. A flight departing Los Angeles at 10:00 AM Tuesday and arriving in Sydney 15 hours later arrives at what would be 1:00 AM Wednesday LA time, but Sydney is UTC+11 while LA is UTC-8, a 19-hour difference. Adding 19 hours to 10:00 AM Tuesday gives 5:00 AM Wednesday Sydney time. The date change is not an error. It is a real consequence of Earth's rotation. Scheduling meetings across multiple time zones requires finding overlapping business hours. If your team includes members in San Francisco (UTC-8), London (UTC+0), and Mumbai (UTC+5:30), the overlap of reasonable working hours is narrow. San Francisco 8:00 AM is London 4:00 PM and Mumbai 9:30 PM. San Francisco 6:00 AM is London 2:00 PM and Mumbai 7:30 PM. In practice, someone always has to take an inconvenient time. Rotating the inconvenience so the same person or region does not always suffer is a common fairness strategy. Some teams record meetings so those in difficult time zones can watch asynchronously. World clock displays show the current time in multiple zones simultaneously. Keeping a world clock widget on your desktop or phone home screen eliminates the need to calculate conversions for your regular contacts. Most operating systems support adding multiple time zone clocks. Slack, Microsoft Teams, and Google Calendar can display participants' local times when scheduling. Time zone abbreviations are ambiguous and should be avoided in formal communication. CST could mean Central Standard Time (UTC-6), China Standard Time (UTC+8), or Cuba Standard Time (UTC-5). IST could mean India Standard Time (UTC+5:30), Irish Standard Time (UTC+1), or Israel Standard Time (UTC+2). BST could mean British Summer Time or Bangladesh Standard Time. Always specify the UTC offset or use the full zone name to avoid confusion. Write '3:00 PM UTC-5' or '3:00 PM Eastern Time' rather than '3:00 PM EST'. UTC as a scheduling standard eliminates conversion confusion. Many international organizations, aviation, military operations, and server logs use UTC exclusively. When you say a server maintenance window is 02:00 to 04:00 UTC, everyone worldwide can convert to their local time without ambiguity. Aviation uses UTC for all flight plans, air traffic control communications, and weather reports, calling it Zulu time (abbreviated Z). Military time zones use letter designations (Alpha through Yankee, skipping Juliet) for each hour offset from Zulu. Programming with time zones requires careful handling. Store all timestamps in UTC in your database. Convert to local time only at the display layer. This prevents errors when users in different zones interact with the same data. Use established libraries (moment-timezone for JavaScript, pytz or zoneinfo for Python, java.time for Java) rather than writing manual offset arithmetic. Edge cases around DST transitions, leap seconds, and historical zone changes are too complex for manual handling. Common programming bugs with time zones include: assuming all days have 24 hours (DST transition days have 23 or 25), assuming time zone offsets are whole hours (India is +5:30, Nepal is +5:45), assuming DST transitions happen at the same time worldwide, storing local time instead of UTC, and parsing date strings without explicit time zone information. Each of these assumptions will produce incorrect results for some users some of the time. The Unix timestamp (seconds since January 1, 1970 00:00:00 UTC) is a time zone-neutral way to represent a moment in time. The timestamp 1700000000 is the same instant everywhere on Earth. Converting it to local time gives different clock readings in different zones, but the underlying moment is identical. This is why servers and APIs commonly exchange timestamps as Unix epoch values or ISO 8601 strings with explicit UTC offset (2026-03-21T15:30:00Z or 2026-03-21T10:30:00-05:00). Travel planning requires understanding time zones at both origin and destination. When you fly from New York to London (5-hour time difference in winter), a 7-hour flight departing at 7:00 PM arrives at 7:00 AM local time the next day. Your body thinks it is 2:00 AM. This mismatch is jet lag. Eastward travel (losing hours) tends to cause worse jet lag than westward travel (gaining hours). A general recovery guideline is one day per time zone crossed. Adjusting your sleep schedule by one hour per day before departure helps reduce jet lag for long trips. Time zones affect financial markets, broadcast schedules, and product launches. The New York Stock Exchange opens at 9:30 AM Eastern, which is 2:30 PM in London, 6:30 AM in Los Angeles, and 10:30 PM in Tokyo. Forex markets are open 24 hours because they follow the sun across Sydney, Tokyo, London, and New York sessions. A global product launch at midnight Pacific Time catches different hours worldwide: 3:00 AM Eastern, 8:00 AM London, 5:00 PM Tokyo. Understanding these relationships helps you plan when to take action. International shipping deadlines and contractual obligations must specify which time zone applies. A contract stating delivery by March 31 is ambiguous if the parties are in different zones. When it is already April 1 in Tokyo, it is still March 31 in Los Angeles. Legal and financial deadlines should always include explicit time zone references. Many legal documents use UTC or a specified location's local time to avoid this ambiguity. Historical time zone changes are surprisingly common. Countries and regions periodically change their UTC offset, adopt or abandon DST, or shift their DST transition dates. Russia has changed its time zone rules multiple times in recent decades, most recently in 2014 when it stopped observing DST and then adjusted some regional offsets. Samoa skipped December 30, 2011, entirely when it shifted from UTC-11 to UTC+13 to align with its major trading partners Australia and New Zealand. Egypt has flip-flopped on DST multiple times. North Korea created its own time zone in 2015 (UTC+8:30) and then switched back to UTC+9 in 2018. These changes mean that historical time conversions cannot use current rules. Daylight saving time abolishment is an ongoing legislative effort in many regions. The US Senate passed the Sunshine Protection Act in 2022 to make DST permanent year-round, but it stalled in the House. The European Union voted in 2019 to abolish seasonal clock changes, allowing each member state to choose permanent standard time or permanent summer time, but implementation has been repeatedly delayed. Arizona and Hawaii already do not observe DST. If DST is eventually abolished in your region, time zone conversion with regions that still observe it will require tracking which regions change and which do not. Remote work across time zones requires deliberate communication practices. Establish core hours when all team members are expected to be available, even if those hours are off-peak for some. Use shared calendars that display events in each viewer's local time. Record all meetings for those who cannot attend live. Set clear response time expectations for asynchronous communication (email, chat). Document decisions in writing so team members in different zones can catch up on their own schedule. Sports broadcasting across time zones means the same event airs at different clock times. The Super Bowl kicking off at 6:30 PM Eastern is 3:30 PM Pacific, 11:30 PM GMT, and 8:30 AM the next day in Tokyo. Olympic events broadcast from a host city in Asia or Europe air during the middle of the night for American viewers. Understanding time zone math helps you set alarms, plan viewing parties, and avoid spoilers for events that have not yet aired in your zone. E-commerce and customer support hours span time zones for global businesses. A support team in India (UTC+5:30) handles tickets during US sleeping hours, providing round-the-clock coverage. Sale start times and promotional deadlines must specify the applicable time zone. A sale ending at midnight PST gives East Coast customers three fewer hours than West Coast customers. Smart businesses display countdown timers that localize to each visitor's browser time zone. Calculating time differences for phone calls requires knowing both the source and destination offsets, which may change seasonally. A call from New York to Dubai (UTC+4, no DST) is a 9-hour difference in winter (EST, UTC-5) and an 8-hour difference in summer (EDT, UTC-4). Keeping a reference card or app with your regular contacts' time zones and their DST status prevents embarrassing middle-of-the-night calls. Medical appointments and prescription timing across time zones require attention. A medication that should be taken every 12 hours at 8 AM and 8 PM in your home time zone does not change to the local clock when you travel. Your body's circadian rhythm follows your home time zone for the first several days of a trip. Gradually shifting medication timing by 1 to 2 hours per day during travel helps maintain consistent dosing intervals. For critical medications (blood thinners, heart medications, insulin), consult your doctor before traveling across multiple time zones. Online exam and deadline proctoring spans time zones. A university offering a global online exam at 9:00 AM Eastern creates very different conditions for students in California (6:00 AM), London (2:00 PM), and Singapore (9:00 PM). Fair assessment policies account for these differences by offering multiple time windows or 24-hour submission periods. Students should always verify which time zone a deadline uses and convert it to their local time well in advance. Server and infrastructure management across time zones requires standard practices. Log timestamps should always be in UTC regardless of server location. Cron jobs and scheduled tasks should reference UTC to avoid DST-related failures (a job scheduled at 2:30 AM local time will be skipped during the spring-forward transition). Database timestamps should store UTC with time zone metadata. Monitoring dashboards should display times in the viewer's local zone while storing UTC internally. These practices prevent the subtle bugs that arise when systems in different zones interact. Cruise ship time zones change during the voyage. Transatlantic cruises crossing multiple time zones adjust the ship's clocks by one hour on selected nights. The ship may announce clocks going forward or back at 2:00 AM. This affects meal times, excursion schedules, and medication timing. When docking at ports, the local time may differ from ship time. Always clarify whether a listed time is ship time or port time for excursions and tours. Social media posting across time zones requires knowing when your audience is active. If your followers are primarily in the US, posting at 9:00 AM Eastern reaches the East Coast during morning commute time but hits the West Coast at 6:00 AM when fewer people are scrolling. Scheduling tools like Buffer and Hootsuite let you set posting times in specific zones and analyze engagement by time of day. For global audiences, posting the same content multiple times at different hours or using evergreen content that performs well regardless of timing addresses the time zone spread. Time zone maps and visualization tools help understand geographic relationships that are not obvious from offset numbers alone. Russia spans 11 time zones (UTC+2 to UTC+12). Canada spans 6 time zones. Brazil spans 4. Indonesia spans 3. Knowing that all of China uses UTC+8 despite spanning 5 geographic zones explains why sunset in western China can be after 10 PM in summer. A visual time zone map reveals these anomalies that pure offset numbers do not convey. The WebRecast time zone converter lets you select a source time zone and a target time zone, enter a time, and see the converted result. It accounts for current UTC offsets including any active DST adjustments. Use it to schedule international calls, determine when a livestream starts in your time zone, or coordinate deadlines across distributed teams. The tool handles the offset arithmetic so you do not have to track which zones are currently observing DST.

Time Zone Converter

Key features

Guide

Frequently asked questions

Which zones?

Related guides

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