Timezone Converter

Your team has a standup at 10:00 AM ET. What time is that for the developer in Berlin, the designer in Tokyo, and the PM in Auckland? You Google “10am ET to JST” and get one conversion. You need the other three. A timezone converter that shows multiple zones simultaneously saves you from doing four separate searches.

Why a Dedicated Converter (Not Just Google)

Google handles simple “X time in Y timezone” queries, but falls short for developer workflows: no batch conversion, no IANA timezone names (it uses abbreviations like “EST” which are ambiguous — EST is both Eastern Standard Time and Eastern Standard Time in Australia), and no awareness of DST transitions on specific dates.

This tool uses the IANA timezone database (the same one used by your operating system and programming languages) and handles DST transitions correctly for any date, past or future.

Features

Multi-zone comparison. Add as many timezones as you need and see the converted time across all of them simultaneously. Useful for distributed teams.

DST-aware conversion. Enter a specific date and the tool accounts for Daylight Saving Time transitions. “3:00 PM EDT” and “3:00 PM EST” are different UTC offsets — this tool gets it right.

IANA timezone names. Use canonical names like America/New_York, Europe/Berlin, Asia/Tokyo — not ambiguous abbreviations. The tool includes all 400+ IANA zones with search and autocomplete.

Meeting planner. Select a time range in one timezone and see which hours are within working hours (9 AM–6 PM) across all added zones. Green = working hours, yellow = early/late, red = sleeping hours.

Common Timezone Offsets

Understanding DST Transitions

Daylight Saving Time creates two tricky edge cases:

Spring forward. When clocks jump from 2:00 AM to 3:00 AM, the time 2:30 AM does not exist. Attempting to schedule a meeting at that time will fail or produce unexpected results.

Fall back. When clocks move from 2:00 AM back to 1:00 AM, the time 1:30 AM occurs twice. Without specifying the offset, the intended time is ambiguous.

This tool flags these edge cases and shows the UTC offset explicitly so there is no ambiguity.

Privacy

All conversions run entirely in your browser using JavaScript’s Intl.DateTimeFormat API. No times, dates, or timezone selections are transmitted to any server.

Frequently Asked Questions

Why should I use IANA timezone names instead of abbreviations? Abbreviations like “CST” are ambiguous — they can mean Central Standard Time (UTC−6), China Standard Time (UTC+8), or Cuba Standard Time (UTC−5). IANA names like America/Chicago are globally unique and unambiguous.

Does this handle historical timezone changes? The tool uses your browser’s built-in IANA database, which includes historical timezone data. Accuracy for dates before 1970 varies by browser and OS.

Can I share a converted time with my team? The tool updates the URL with your current configuration so you can copy the URL and share it. Recipients will see the same timezones and time.

How does DST affect UTC offsets? UTC itself never changes. When a timezone observes DST, its offset from UTC changes. For example, US Eastern is UTC−5 in winter (EST) and UTC−4 in summer (EDT). Always store and transmit times in UTC to avoid confusion.

What timezone database does this use? This tool uses the IANA Time Zone Database (also known as the Olson database or tz database), maintained by ICANN. It is the same database used by Linux, macOS, Java, and most programming languages.