Time Zone Converter

How Time Zone Conversion Works

The world runs on 24+ primary time zones, and coordinating across them is a daily challenge for remote teams, international businesses, travelers, and anyone with family overseas. Adding to the complexity, daylight saving time shifts the offset twice a year — and not every country observes it, and those that do change clocks on different dates. This converter handles all of it: select a time and zone, pick one or more target zones, and see the equivalent time instantly. It accounts for DST automatically using the IANA time zone database, so the result is correct whether you are converting in January or July.

Quick example: It is 3 PM in New York. What time is it in Tokyo? The answer depends on the date — in January, Tokyo is 14 hours ahead (5 AM the next day). In July, due to DST in New York but not in Tokyo, the gap narrows to 13 hours (4 AM the next day). The converter tracks these shifts automatically.

Understanding Time Zones and UTC

Time zones are regions of the Earth that observe the same standard time. They are defined as offsets from Coordinated Universal Time (UTC), which replaced Greenwich Mean Time (GMT) as the global reference standard. UTC+0 runs through London (when not on summer time). Zones to the east are ahead (UTC+1, +2, etc.), and zones to the west are behind (UTC−1, −2, etc.).

Most time zones are offset by whole hours, but several use 30- or 45-minute offsets: India (UTC+5:30), Nepal (UTC+5:45), Iran (UTC+3:30), parts of Australia (UTC+9:30), and the Chatham Islands (UTC+12:45). These fractional offsets are one of the reasons manual conversion is error-prone — the converter handles them seamlessly.

UTC itself does not observe daylight saving time, which is why it serves as a stable anchor for international coordination. When scheduling across 3+ time zones, expressing times in UTC eliminates all ambiguity: “Meeting at 14:00 UTC” means the same thing to everyone regardless of where they are.

Major Time Zone Quick Reference

Here are the most commonly referenced time zones. Remember that the DST column shows the summer offset for zones that observe daylight saving time — the standard offset applies during winter months.

North America: Eastern (EST UTC−5 / EDT UTC−4) covers New York, Toronto, Miami. Central (CST UTC−6 / CDT UTC−5) covers Chicago, Dallas, Mexico City. Mountain (MST UTC−7 / MDT UTC−6) covers Denver, Phoenix (no DST). Pacific (PST UTC−8 / PDT UTC−7) covers Los Angeles, Seattle, Vancouver.

Europe: Greenwich/British Summer (GMT UTC+0 / BST UTC+1) covers London, Dublin, Lisbon. Central European (CET UTC+1 / CEST UTC+2) covers Paris, Berlin, Madrid, Rome. Eastern European (EET UTC+2 / EEST UTC+3) covers Athens, Helsinki, Bucharest. Moscow (MSK UTC+3, no DST) covers Moscow, Istanbul.

Asia-Pacific: India Standard (IST UTC+5:30, no DST) covers Mumbai, Delhi, Bangalore. China Standard (CST UTC+8, no DST) covers Beijing, Shanghai, Hong Kong. Japan Standard (JST UTC+9, no DST) covers Tokyo, Osaka. Australian Eastern (AEST UTC+10 / AEDT UTC+11) covers Sydney, Melbourne. New Zealand (NZST UTC+12 / NZDT UTC+13) covers Auckland.

Daylight Saving Time: The Complication

Daylight saving time (DST) shifts clocks forward by one hour in spring and back in fall. The complication for conversions is that not all countries observe DST, and those that do change on different dates, creating weeks where the usual time difference is temporarily wrong if you do not account for the transition.

U.S. and Canada: Clocks spring forward on the second Sunday of March and fall back on the first Sunday of November. Europe: Spring forward on the last Sunday of March, fall back on the last Sunday of October. No DST: Most of Asia (China, Japan, India, South Korea), most of Africa, Russia, Iceland, and the U.S. states of Arizona and Hawaii. Southern Hemisphere: Australia and New Zealand observe DST on the opposite schedule — spring forward in October, fall back in March/April.

This means there are several weeks each year when the hour difference between two zones is different from its usual value. For example, the New York–London difference is usually 5 hours. But for the 2–3 weeks in March when the U.S. has already sprung forward but Europe has not, the difference is only 4 hours. The converter handles all of these edge cases automatically using the IANA database.

Finding Meeting Times Across Time Zones

The hardest coordination problem is finding a time when multiple participants across different zones are all within business hours (roughly 9 AM – 6 PM local). For a New York + London + Tokyo meeting, there is no single time that falls within standard business hours for all three zones simultaneously because New York and Tokyo are 14 hours apart.

Best compromises: Early morning New York (7–8 AM) with late evening Tokyo (9–10 PM), or hold two separate meetings. For New York + London alone, the overlap window is generous — roughly 9 AM – 1 PM New York time (2–6 PM London time). For London + Tokyo, 8–11 AM London works (5–8 PM Tokyo).

The meeting planner mode performs this overlap analysis automatically. Enter each participant’s zone and available hours, and the converter highlights any overlap, taking DST into account for the specific date of the meeting.

Tips for Working Across Time Zones

Use UTC as your anchor. When coordinating with people in 3+ zones, express times in UTC and let each person convert locally. This eliminates the ambiguity of abbreviations like CST (which can mean Central Standard Time in the U.S. or China Standard Time).

Beware the date line. When converting between zones that span the International Date Line (e.g., Los Angeles to Sydney), the date changes. A Friday afternoon call in LA is a Saturday morning call in Sydney. Always confirm the date, not just the time.

Rotate meeting times for fairness. If your team spans the globe, no single time is fair to everyone. Rotating meeting times ensures no one zone consistently takes the inconvenient slot. Document the rotation schedule so everyone knows when their convenient slot is coming.

Block your calendar in the other person’s time zone. Many calendar apps let you display a secondary time zone. Use this to avoid accidentally scheduling over someone else’s evening or weekend. Seeing both zones side by side on your calendar prevents most coordination errors.