Clever Quest Lab Tools

Time Zone Converter

2026-10-17

Convert a date and time from one time zone to several others at once. Each zone shows its UTC offset, abbreviation, daylight saving status and next clock change, and the meeting planner finds hours that fall inside working hours everywhere.

Convert a date and time

Type a city, country, abbreviation (EST, IST, CET) or UTC offset (UTC+5:30) and pick a result.

    Compare up to 12 time zones.
    Clock

    Everything is calculated in your browser with its built-in time zone rules — nothing you enter is sent to a server.

    Meeting planner

    One row per time zone.

    • Working hours
    • Morning and evening
    • Night (22:00–06:00)
    • Selected hour
    • Working hours in every zone

    How to use the time zone converter

    1. Choose the main time zone — the zone of the time you want to convert. Type a city ("Chicago"), a country ("Brazil"), an abbreviation ("PST") or an offset ("UTC+5:30") and pick a result. It starts as the zone your device reports.
    2. Set the date and time. Until you change them, the converter shows the current time and keeps it up to date; "Now" brings that back.
    3. Add places with Add a time zone. Each card shows the local time and date, the UTC offset, the abbreviation, the daylight saving status, the next clock change and the difference from the main zone. Make main lets you type a time for that zone instead; Remove drops it.
    4. In the meeting planner, set the working hours and look for columns marked ✓ — at those hours every zone is inside its working hours. Click or tap an hour (or use the arrow keys and Enter) to make it the time above. Weekends and public holidays are not taken into account.
    5. Copy times copies a plain-text list; Copy link copies an address that opens the page with the same zones and time.

    How it works

    Every time zone is described by its offset from Coordinated Universal Time (UTC) at a given moment. Local time is UTC plus that offset, so a conversion always goes through UTC:

    target time = source time − offset(source) + offset(target)

    offset(source) and offset(target) are the UTC offsets of the two zones at that exact moment, for example +5:30 for India or −4 for New York in summer. Offsets change when daylight saving time starts or ends, so they must be looked up for the exact date.

    The converter has no rule table of its own. It asks your browser, which ships with the IANA time zone database (zone names such as Europe/Berlin come from it), through Intl.DateTimeFormat: it formats a moment in a zone, reads the local date and time back, and the difference from UTC is the offset. To turn a local time into a moment, it tries the offsets the zone uses a day earlier and a day later and keeps each one that gives back exactly the time you typed.

    Usually one offset fits. If none fits, the time falls into the gap of a spring clock change and does not exist; the converter then uses the offset from before the change, which moves the time forward by the length of the gap (02:30 becomes 03:30). If two fit, the time happens twice during an autumn change; the first occurrence is used and you can switch to the second.

    Examples

    Example 1 — a call across three continents. Wednesday 15 July 2026, 09:00 in New York (EDT, UTC−4) is 13:00 UTC. That is 14:00 in London (BST, UTC+1), 18:30 in Kolkata (IST, UTC+5:30) and 22:00 in Tokyo (JST, UTC+9).

    Example 2 — quarter-hour offsets. Wednesday 1 July 2026, 12:00 in Kolkata (UTC+5:30) is 06:30 UTC: 12:15 in Kathmandu (NPT, UTC+5:45) and 19:15 on the Chatham Islands (CHAST, UTC+12:45). On 15 January 2026 the Chatham Islands are on summer time (CHADT, UTC+13:45), so 12:00 in Kolkata is 20:15 there.

    Example 3 — a time that does not exist. On Sunday 29 March 2026 the clocks in Berlin jump from 02:00 to 03:00. If you enter 02:30, the converter explains the gap and uses 03:30 CEST (UTC+2), which is 01:30 UTC and 21:30 on Saturday 28 March in New York (EDT, UTC−4).

    Example 4 — a time that happens twice. On Sunday 1 November 2026 New York turns its clocks back from 02:00 to 01:00, so 01:30 happens twice. The first 01:30 is EDT (UTC−4) = 05:30 UTC = 05:30 in London; the second is EST (UTC−5) = 06:30 UTC = 06:30 in London.

    Daylight saving time: when the difference changes

    Places that use daylight saving time (DST) do not all switch on the same day:

    So between 8 and 29 March and between 25 October and 1 November 2026, New York is 5 hours behind Berlin instead of 6: 15:00 in Berlin on Friday 20 March 2026 is 10:00 in New York, not 09:00. Between Europe and south-eastern Australia the difference changes by two hours over the year.

    Some offsets are not whole hours: India UTC+5:30, Nepal UTC+5:45, Newfoundland UTC−3:30, Iran UTC+3:30, Afghanistan UTC+4:30, Myanmar UTC+6:30, central Australia UTC+9:30 and the Chatham Islands UTC+12:45 (UTC+13:45 in summer). Lord Howe Island moves its clocks by only 30 minutes. In the planner, such zones show hours that start at :30 or :45.

    Why abbreviations can mislead

    Time zone abbreviations are neither unique nor official. IST stands for India Standard Time (UTC+5:30), Irish Standard Time (UTC+1, in summer) and Israel Standard Time (UTC+2). CST can be US Central Standard Time (UTC−6), China Standard Time (UTC+8) or Cuba Standard Time (UTC−5), and BST is British Summer Time (UTC+1) or Bangladesh Standard Time (UTC+6). When you search for such an abbreviation, the converter lists every meaning it knows instead of guessing. They are also used loosely: "EST" in a July invitation usually means US Eastern time, which is really EDT (UTC−4) in summer. Writing the city or the UTC offset is safer.

    Frequently asked questions

    Is UTC the same as GMT?

    For converting clock times, yes — both have an offset of zero. UTC is the international time standard kept by atomic clocks; GMT is the time zone used in the UK in winter and in several West African countries all year. They differ by less than a second.

    Why does a card show +1 day or −1 day?

    At that moment the date there differs from the date in the main zone: Monday evening in Los Angeles is already Tuesday in Tokyo. Offsets in use run from UTC−11 to UTC+14, so two places can even be two calendar days apart.

    How up to date are the time zone rules?

    They are the rules built into your browser, updated with browser releases. Governments sometimes change rules at short notice, so for dates far ahead an outdated browser can give a different answer. Nothing is downloaded; once loaded, the page works offline.

    Can I send the meeting time to other people?

    Yes. "Copy link" copies an address with the zones and the time, so others see the same moment converted on their own device.

    Is my data sent anywhere?

    No. All calculations run in your browser. Your zones, the chosen time and your settings are remembered only in your browser's local storage, and nothing is uploaded to a server.

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