World Clock

World Clock

Use this world clock to compare current local times across major cities. Search by city or IANA time-zone name, then narrow the list by region. Each card shows the local time, calendar date, UTC offset, and a simple morning, afternoon, evening, or night indicator.

The clock reads the browser's built-in internationalization data instead of performing a fixed UTC subtraction. That distinction matters because many locations change their UTC offset when daylight-saving rules begin or end.

How to compare time zones

1. Search for a city such as Tokyo, London, or America/New_York.
2. Choose a region to reduce the number of visible cards.
3. Check both the date and offset before scheduling an event.

Task	What to verify
Scheduling a meeting	Local time and date for every participant
Working with a remote team	City or IANA zone, not only a UTC offset
Planning travel	Seasonal daylight-saving changes
Publishing globally	The destination's local calendar date

UTC offsets versus time zones

A UTC offset such as UTC−04:00 is only a snapshot. A named time zone such as America/New_York contains the regional rules needed to determine the correct offset for a particular date. Two cities can share an offset today and differ later after a daylight-saving transition.

Browser implementation

The page uses the standard Intl.DateTimeFormat API. The timeZone option handles conversion and locale-aware formatting:

const formatter = new Intl.DateTimeFormat("en-US", {
  dateStyle: "medium",
  timeStyle: "long",
  timeZone: "Asia/Tokyo",
});

console.log(formatter.format(new Date()));

The same API works in TypeScript:

function currentTime(zone: string): string {
  return new Intl.DateTimeFormat("en-US", {
    hour: "2-digit",
    minute: "2-digit",
    second: "2-digit",
    timeZone: zone,
  }).format(new Date());
}

Python applications can use the IANA database through zoneinfo:

from datetime import datetime
from zoneinfo import ZoneInfo

tokyo = datetime.now(ZoneInfo("Asia/Tokyo"))
print(tokyo.strftime("%Y-%m-%d %H:%M:%S %Z"))

Common mistakes

• Comparing times without checking whether the date crossed midnight.
• Treating a current offset as a permanent property of a city.
• Using an abbreviation such as CST, which can describe multiple zones.
• Forgetting that regions may change daylight-saving policies.

Frequently asked questions

Does this clock account for daylight saving time?

Yes. The browser's current time-zone database applies the relevant rules for the displayed date. Results can differ from a manual UTC calculation during seasonal transitions.

Does it include every time zone?

No. The tool presents a curated set of major cities across five regions. Use a named IANA zone in a dedicated time-zone converter when a city is not listed.

How often does the display update?

Visible cards refresh once per second while the page remains open. Search and region filters update immediately without changing the underlying clock.