Time Zone Converter (world cities, daylight saving aware)

Understanding the time zone converter — concept and principle

This converter shows what time it is in major world cities for a chosen date and local time. Use it to schedule international meetings, check flight arrival times or plan a live stream. Daylight saving time is applied for the exact date you choose.

Every city adds its own offset to the same UTC instant, so the date can differ. The page starts from the current time.

How it is calculated

The calculator treats your input as a wall-clock time in the selected city, finds that city's UTC offset on that date, and subtracts it to get UTC: UTC = local time − offset. It then adds each other city's offset for the same instant: other local time = UTC + offset(other). Offsets come from your browser's built-in IANA time zone database through the Intl API. The lookup is repeated once so that times near a daylight-saving switch resolve correctly.

The principle

Time zones are offsets from Coordinated Universal Time (UTC), the atomic-clock reference timescale. Most zones are whole hours from UTC, but some are not: India uses UTC+05:30 and Nepal UTC+05:45. Many regions move clocks forward one hour in summer (daylight saving time), on dates that differ by country. The IANA database records these rules and their history for each region, such as Asia/Seoul or America/New_York, which is why an accurate converter must know the date, not just the city.

Worked example

Default inputs: 9 November 2026, 04:17 in Seoul. (The page starts with the current time, so your default may differ.)

Seoul uses UTC+09:00 all year; Korea has no daylight saving time.
UTC = 04:17 − 9 h = 19:17 UTC, on Sunday 8 November.
Tokyo is also UTC+09:00, so Mon 9 Nov, 04:17. Beijing and Singapore (UTC+08:00) show 03:17; Delhi (UTC+05:30) shows 00:47.
Dubai (UTC+04:00) is Sun 8 Nov, 23:17, and Moscow (UTC+03:00) 22:17.
New York has left daylight saving by this date, so it is UTC−05:00: 19:17 − 5 h = 14:17 on Sunday.

How to read the result

Check the weekday and date as well as the clock: crossing the date line or midnight often changes the day. The offset next to each city tells you whether daylight saving is in force on that date.

Common mistakes

Assuming the time difference is fixed all year; Seoul to London is 9 hours in winter but 8 in summer.
Entering the time for the wrong city in the "In this city" box.
Forgetting that times in the spring "gap" (when clocks jump forward) do not exist locally.

Keep in mind: Results follow the time zone rules built into your browser. Governments sometimes change daylight-saving rules at short notice, so double-check critical times such as flights or legal deadlines with official sources.

Frequently asked questions

What is the time difference between Seoul and New York?

14 hours while New York is on standard time and 13 hours during US daylight saving time.

Does Korea use daylight saving time?

No. Korea stays on UTC+09:00 all year, as do Japan and China (UTC+08:00).

Is UTC the same as GMT?

For everyday scheduling they show the same clock time, but UTC is the atomic-clock-based standard, while GMT is also the name of the UK's winter time zone.

Sources: IANA Time Zone Database (tz database) · BIPM, Coordinated Universal Time (UTC) and the SI Brochure, 9th edition, 2019 · ISO 8601, Date and time — Representations for information interchange

Checked 8 Nov 2026. IANA Time Zone Database (via the browser’s Intl API).