How do I use the world clock calculator?

Choose a base city or time zone, set the date and time, then add other cities. The tool instantly shows the corresponding local time in every city. You can drag rows to reorder, toggle 12/24‑hour format, and apply time offsets to plan future or past meetings.

Does this world clock handle daylight saving time (DST)?

Yes. The calculator uses the browser's IANA time zone database via Intl.DateTimeFormat, which automatically applies the correct daylight saving time rules for the selected date in each city.

Can I compare more than two time zones at once?

You can add as many cities or time zones as you like. Each appears as a row in the comparison table, showing local time, UTC offset, and whether it is currently today, yesterday, or tomorrow relative to the base time.

How do I find overlapping working hours across time zones?

Set a base time and then drag the time slider or use the +/− hour buttons to move through the day. Watch the colored "local time" badges: green indicates typical working hours (09:00–17:00), yellow for early/late, and gray for night. This makes it easy to spot overlapping business hours.

What is the difference between UTC offset and time zone?

UTC offset is the numeric difference from Coordinated Universal Time, such as UTC+1 or UTC−5. A time zone, like America/New_York or Europe/London, is a region that follows specific rules for standard time and daylight saving time. The same time zone can have different UTC offsets at different times of the year.

World Clock Calculator – Multi‑City Time Zone Converter

How to use the world clock calculator

Pick a base city or time zone. This is the reference time for your meeting or event.
Set the date and time. You can use the date/time pickers or the quick +/− buttons.
Add cities. Tap any quick city pill or type a city/time zone name and click “Add city”.
Compare local times. The table shows local time, day (yesterday/today/tomorrow), UTC offset, and the difference from the base time.

Features that make this world clock more useful

Multi‑city comparison: Add as many cities as you need for global meetings.
Daylight saving aware: Uses the browser’s time zone database to apply the correct DST rules for the selected date.
12/24‑hour toggle: Instantly switch between 12‑hour (AM/PM) and 24‑hour formats.
Quick time shifting: Move the base time in 15‑minute or 1‑hour steps to find overlapping working hours.
Relative day indicator: See at a glance if it’s yesterday, today, or tomorrow in each city.

Understanding UTC offsets and time zones

Coordinated Universal Time (UTC) is the reference for all time zones. A time zone’s UTC offset tells you how many hours it is ahead of or behind UTC.

Local time = UTC time + UTC offset

For example, if it is 12:00 (noon) UTC:

New York in winter (UTC−5) → 07:00 local time
London in winter (UTC+0) → 12:00 local time
Tokyo (UTC+9) → 21:00 local time

Because of daylight saving time, the same city can have different UTC offsets at different times of the year. That’s why using named time zones (like America/New_York) is more reliable than fixed numeric offsets.

Tips for scheduling meetings across time zones

Check the date carefully. A time that is Monday morning in one city may already be Monday evening or even Tuesday in another.
Aim for overlapping working hours. Use the time shift buttons to slide the meeting time until most cities are in daytime.
Be mindful of DST changes. Around March/April and October/November, some regions change clocks on different dates.

World Clock Calculator FAQ

Related Lifestyle & Everyday Tools

Why use a world clock calculator?

When your team, clients, or friends are spread across continents, guessing time zones leads to missed calls and confusion.

This tool lets you see everyone’s local time for any date in one view, making it easier to pick fair meeting times and avoid surprises from daylight saving changes.

Quick add cities

How to use the world clock calculator

Features that make this world clock more useful

Understanding UTC offsets and time zones

Tips for scheduling meetings across time zones

World Clock Calculator FAQ