World Clock & Time Difference Calculator
Last updated: 2026-06-25
The world clock shows the current time in major cities in each city's local time and automatically calculates the time difference between any two cities you choose. Daylight saving is applied based on the current date.
Korea Standard Time (KST) is UTC+9 and stays the same all year.
Compare time zones
Time difference
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Current time in major cities
| City | Current time | vs. Seoul |
|---|
How to use
- Choose the base city — select the base city (Seoul by default).
- Choose the comparison city — select the city you want to compare against.
- View the result — the current time in both cities and the time difference (hours ahead/behind) appear in real time.
How world time and time differences work
The world is divided into 24 time zones, and each region's standard time is defined as ± a number of hours from Coordinated Universal Time (UTC). Korea Standard Time (KST) is UTC+9, the UK (GMT) is UTC+0 and the US East Coast is UTC-5 in winter. This calculator uses the IANA time-zone data exposed by the browser's Intl.DateTimeFormat to convert the current moment into each city's actual standard time.
| City | UTC offset | Daylight saving |
|---|---|---|
| Seoul / Tokyo | UTC+9 | None |
| Beijing / Singapore | UTC+8 | None |
| London | UTC+0 | +1 in summer (BST) |
| New York | UTC−5 | +1 in summer (EDT) |
| Los Angeles | UTC−8 | +1 in summer (PDT) |
| Sydney | UTC+10 | +1 in summer (Southern Hemisphere) |
Regions that observe daylight saving time shift their offset by an hour depending on the season. This tool always reflects the current date automatically, so it is handy for international video calls or checking flight times. If you need to split costs for a meeting, try the bill splitter too.
Frequently asked questions (FAQ)
How is the time difference calculated?
The tool finds how many hours each city's standard time is offset from Coordinated Universal Time (UTC), then takes the difference between the two cities. Cities that use daylight saving time may shift by an hour depending on the season, and this tool reflects the current date automatically.
What UTC offset does Seoul use?
Korea Standard Time (KST) is UTC+9. Korea does not observe daylight saving time, so it is always 9 hours ahead of UTC year-round.
Is daylight saving time included?
Yes. This calculator uses the browser's Intl.DateTimeFormat time-zone support to apply the actual current standard time and daylight saving automatically. For example, New York is UTC-4 in summer (EDT) and UTC-5 in winter (EST).
Is the time accurate?
The displayed time converts your device clock to UTC and then back to each city's time zone, so it is only as accurate as your device clock.
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Last updated: 2026-06-25